FNGINES 


CONSTRUCTION,  CARE  AND  OPERATION 

WITH  OyESTlONSAND  ANSWERS 

SWINGLE 


UNIVERSITY  OF  CALIFORNIA.  LIBRARY 

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03 


LIBRARY 

OF  THE 

UNIVERSITY  OF  CALIFORNIA. 

Class 


STEAM  TURBINE 
ENGINES 

Their  Construction,  Care  and  Operation 


The  principles  governing  the  Action  of  the  Steam  in  the 

various  types  of  Steam  Turbines  are  clearly  set 

forth  in  plain  language,  not  too  technical 

for  the   man  with  an  ordinary 

education  to  understand. 


Full  Instructions  Regarding  Correct 
Methods  of  Operating  Steam  Turbines, 
Adjusting  Clearances,  etc.,  etc. 


BY 

CALVIN    F.     ^WINGLE 

Author  of  "Twentieth  Century  Hand  Book  for  Steam  Engineers  and 

Electricians,"    "Modern  Locomotive  Engineering," 

"Modern  Steam  Boilers"  and  "Catechism 

for  Engineers  and  Electricians." 


OFTHC 

UNIVERSITY 

OF 


CHICAGO 

FREDERICK  J.  DRAKE  &  COMPANY 


JCOPYRIGHT  1910 
BY 

FREDERICK  J.  DRAKE  &  Co. 


INTRODUCTION 


The  rapid  increase  within  recent  years,  in  the  number  of 
installations  of  steam  turbines  for  power  purposes,  renders 
it  absolutely  necessary  that  the  engineer  who  is  in  charge 
of,  or  is  confronted  with  a  possibility  of  being  placed  in 
charge  of  a  steam  turbine  plant,  should  make  himself 
thoroughly  acquainted  with  the  principles  controlling  the 
action  of  steam  turbines;  also  the  details  connected  with 
their  care,  and  successful  operation.  This  knowledge  he 
can  obtain  by  a  close  study  of  the  following  pages,  in  which 
are  set  forth  in  plain,  simple  language  the  underlying  prin- 
ciples of  the  turbine,  and  its  advantages  as  a  prime  mover. 
The  book  also  contains  descriptions  in  detail  of  the  several 
different  types  of  steam  turbines  that  have,  on  account  of 
their  merits  come  to  be  standard  in  this  country.  Each 
type  is  clearly  illustrated  and  explained.  There  is  also  a 
plain  and  forcible  discussion  of  methods  used  in  the  dis- 
posal of  the  exhaust  steam  of  steam  turbines,  much  of  which 
will  also  apply  to  reciprocating  engines,  and  this  in  itself 
will  prove  to  be  of  great  benefit  to  the  student  engineer, 
for  the  reason  that  in  many  steam  plants  conditions  exist 
which  call  for  a  complete  working  knowledge  of  both  the 
Turbine,  and  the  Eeciprocating  types  of  prime  movers,  due 
to  the  fact  that  both  types  of  engines  are  often  being 
operated  by  the  same  firm  or  corporation.  In  addition  to 
the  foregoing  matter,  there  is  also  a  complete  list  of  ques- 
tions and  answers  pertaining  to  the  principles  of  steam 
turbines,  and  their  operation  and  management,  all  of  which 
will  be  found  to  be  of  inestimable  value  to  the  student  seek- 
ing knowledge  along  this  line. 

217106 


OF  THE 

UNIVERSITY 

OF 

The  Steam  Turbine 

Although  the  turbine  principle  of  utilizing  the  heat 
energy  in  steam  and  converting  it  into  useful  work  has 
been  experimented  upon  for  many  years,  it  is  only  since 
the  inauguration  of  the  twentieth  century  that  steam  tur- 
bines have  been  brought  to  the  front  as  efficient  power 
producers. 

The  piston  of  the  reciprocating  engine  is  driven  back 
and  forth  by  the  static  expansive  force  of  the  steam,  while 
in  the  steam  turbine  not  only  the  expansive  force  is  made 
to  do  work,  but  a  still  more  important  element  is  utilized, 
viz.,  the  kinetic  energy,  or  heat  energy  latent  in  the  steam, 
and  which  manifests  itself  in  the  rapid  vibratory  motion  of 
the  particles  of  steam  expanding  from  a  high,  to  a  low 
pressure,  and  this  motion  the  steam  turbine  transforms 
into  work. 

Notwithstanding  the  fact  that  much  has  been  said  and 
written  during  the  past  four  years  regarding  the  steam 
turbine,  the  machine  is  to-day  a  mystery  to  thousands  of 
engineers,  not  because  they  do  not  desire  information  upon 
the  subject,  but  because  of  a  lack  of  opportunities  for  ob- 
taining that  information.  The  author  therefore  considers 
that  a  space  devoted  to  this  subject  would  no  doubt  be  of 
benefit  to  his  readers. 

The  steam  turbine  is  simple  and  compact  in  design,  hav- 
ing few  working  parts  as  compared  with  the  reciprocating 
engine,  and  any  engineer  who  is  capable  of  operating  and 
caring  for  an  engine  of  the  latter  type,  can  also  run  and 
take  care  of  a  steam  turbine.  But,  as  in  the  case  of  the 

7 


Steam  Engineering 


FIG.  235 
FOUR  WESTINGHOUSE-PABSONS  STEAM  TURBINES 


Principle  of  9 

reciprocating  engine,  the  engineer  in  charge  of  a  turbine 
plant  should  be  familiar  with  the  interior  construction  of 
the  machines  under  his  charge,  and  he  should  know  what 
to  do,  and  what  to  avoid  in  order  to  keep  them  in  continual 
and  efficient  operation. 


FIG.  236  / 

The  steam  turbine  in  principle,  and  even  in  type  is  not 
new,  being  in  fact  the  first  heat  motor  of  which  we  have 
any  record  in  steam  engineering. 

One  of  the  earliest  descriptions  of  a  device  for  convert- 
ing the  power  of  steam  into  work  was  recorded  by  Hero, 
a  learned  writer  who  flourished  in  the  city  of  Alexandria 


10 


titeam  Engineering 


in  Egypt,  in  the  second  century  before  Christ.  Hero  de- 
scribes a  machine  called  an  Aeolipile  or  "Ball  of  Aeolus." 
illustrated  in  Fig.  236.  B  is  the  boiler  under  which  a 
fire  was  made.  G  is  a  hollow  metallic  globe  that  revolved 
on  trunnions  C  and  D,  one  of  which  terminated  in  a  pivot 
at  E,  while  the  other  was  hollow  and  conveyed  the  steam 
generated  in  the  boiler  B  to  the  interior  of  the  globe  or 
ball,  from  which  it  escaped  through  the  hollow  bent  tubes 
H  and  I,  and  the  reaction  of  the  escaping  steam  caused  the 


FIG.  237 

globe  to  revolve.     This  was  the  first  steam  turbine,  and 
it  worked  on  the  reaction  principle. 

Many  centuries  later,  in  the  year  A.  D.  1629,  Braiu-n, 
an  Italian,  described  an  engine  which  marks  a  change  in 
the  method  of  using  the  steam.  Branca's  engine  consisted 
of  a  boiler  A,  Fig.  237,  from  which  the  steam  issued  through 
a  straight  pipe,  and  impinged  upon  the  vanes  of  a  hori- 
zontal wheel  carried  upon  a  vertical  shaft,  causing  it  to 
revolve.  This  device  was  the  germ  of  the  impulse  tur- 


Principle  of  11 

bine,  and  these  two  principles,  viz.,  reaction  and  impulse, 
either  one  or  the  other,  and  sometimes  a  combination  of 
both,  are  the  fundamental  principles  upon  which  the  suc- 
cessful steam  turbines  of  the  present  age  operate. 

Steam  expanding  through  a  definite  range  of  tempera- 
ture and  pressure  exerts  the  same  energy  whether  it  issues 
from  a  suitable  orifice  or  expands  against  a  receding  piston. 

Two  transformations  of  energy  take  place  in  the  steam 
turbine;  first,  from  thermal  to  kinetic  energy;  second, 
from  kinetic  energy  to  useful  work.  The  latter  alone  pre- 
sents an  analogy  to  the  hydraulic  turbine. 

The  radical  difference  between  the  two  turbines  lies  in 
the  low  density  of  steam  as  compared  to  water,  and  the 
wide  variation  of  its  volume  under  varying  temperatures 
and  pressures. 

A  cubic  foot  of  steam  under  100  Ibs.  pressure,  if  allowed 
to  discharge  into  a  vacuum  of  28  inches,  would  attain  a 
theoretical  velocity  of  3,860  feet  per  second  and  would 
exert  59,900  ft.  Ibs.  of  energy. 

A  law  of  turbo-mechanics  specifies  that  in  order  to  ob- 
tain the  highest  efficiency  in  the  operation  of  turbines 
(whether  water  or  steam)  the  relation  between  bucket 
speed  and  fluid  speed,  (steam  in  this  case),  should  be  as 
follows : 

For  purely  impulse  wheels,  bucket  speed  equals  one-half 
of  jet  speed. 

For  reaction  wheels,  bucket  speed  equals  jet  speed. 

Assuming  the  velocity  of  the  jet  of  steam  issuing  from 
the  nozzle  to  be  4.000  feet  per  second,  this  would  mean 
a  peripheral  speed  of  2,000  feet  per  second  for  an  im- 
pulee  wheel,  and  for  a  wheel  1  foot  in  diameter  the  speed 
would  be  38,100  R.  P.  M.  But  such  a  speed  is  beyond 


12 


Steam  Engineering 


the  limits  of  strength  of  material,  and  the  speed  of  steam 
turbines  is  accordingly  kept  within  the  bounds  of  safety, 
and  strength  of  material. 

Form  of  Blade. — The  blades  or  buckets  should  be  of 
such  form,  and  curvature  as  will  permit  the  steam  to  ex- 
pand to  the  desired  final,  or  terminal  pressure  with  the 
smallest  possible  friction  and  eddy  current  losses.  As  to 
directing  the  flow  in  the  desired  course,  the  direction  of 


FIG.  238 


exit  from  the  guide,  and  rotating  wheel  is  of  the  greatest 
importance.  In  order  to  get  the  desired  angle,  the  last 
part  of  the  blade  should  be  kept  straight,  at  least  to  the 
foot  of  the  perpendicular  dropped  from  A1?  or  the  length 
A  B  in  Fig.  238.  From  there  on,  the  channel  should  lead 
in  easy  curvature  to  the  angle  av  The  construction  ac- 
cording to  a  in  Fig.  238  would  obviously  be  too  sharp,  and 
would  cause  the  steam  stream  to  separate  from  the  wall. 


Construction  13 

The  construction  according  to  b  would  suffice,  and  the 
wheel  radius  would  depend,  above  all,  upon  how  far  we 
wish  to  dimmish  the  shock  at  entrance.  For  the  profile  b 
the  angle  a±  is  taken  as  the  slope  of  the  blade  back,  from 
which  we  obtain  for  the  guiding  blade  surface  the  some- 
what large  angle  a/.  This  would  be  more  favorable  with  c, 
and  d,  but  the  latter  would  obviously  give  a  needlessly 
long  steam  path.  Besides,  a  pointing  of  the  blade  such 
that  a±  is  half  of  a/,  as  is  shown  dotted  at  d,  could  be  con- 
sidered just  as  correct  as  the  first  mentioned.  By  drawing 
the  absolute  steam  path  and  finding  the  decrease  of  peri- 
pheral speed,  we  get  useful  results  concerning  the  regu- 
larity of  delivering  work. 

The  proper  length  of  the  channel,  or  steam  path  can 
only  be  determined  by  practical  experience,  and  with  a 
given  curvature  the  ratio  of  length  to  breadth  can  be  con- 
sidered fairly  constant. 
1* 

Stuffing  Boxes. — The  stuffing  boxes  are  the  most  im- 
portant and .  delicate  part  of  the  steam  turbine.  As  they 
are"  subjected  to  high  temperature  on  account  of  their 
proximity  to  the  steam  space,  the  problem  of  getting  rid  of 
their  own  heat  of  friction  becomes  all  the  more  difficult. 
The  advantage  of  the  stuffing  box  used  on  reciprocating 
engines,  where  the  rod  for  part  of  the  time  is  exposed  to 
the  air,  and  cools  at  least  its  surface  by  radiation,  cannot 
be  considered  with  the  rotating  shaft.  Water-cooling  may 
be  an  effective  means,  but  creates  considerable  loss  by  con- 
densation in  the  surrounding  steam  spaces. 

The  majority  of  designers  get  around  this  difficulty  by 
avoiding  contact  between  packing  and  shaft,  and  secure 
tightness  only  by  the  least  possible  clearance.  This  is  the 
principle  of  the  so-called  "labyrinth  stuffing  box"  that  was 


1-1  tilcdiii  Engineering 

first  generally  used  by  Parsons.     This  is  shown  in  Fig. 
239,  in  which  A  is  the  shaft,  B  the  stuffing  hox.    The  rings 


y    x     y 
FIG.  239 
LABARYNTH   STUFFING  BOX 


on  both  parts  form  alternately  a  narrow  space  x,  and  a 
large  space  y.  The  velocity  of  the  steam  flowing  through 
this  narrow  space  is  destroyed  by  eddy-currents  in  the 


FIG.  240 


FIG.  241 


large  space,  so  that  for  further  velocity,  a  part  of  the  drop 
in  pressure  is  utilized.  With  a  large  number  of  rings, 
and  with  very  small  spaces  x,  the  loss  is  greatly  decreased. 


Construction 


15 


It  also  seems  to  have  a  favorable  influence  when  the  steam 
in  leaving  this  narrow  space  flows  radially  inwards,  that  is, 
it  helps  to  overcome  its  centrifugal  force. 

Fig.  240  shows  the  stuffing  hox  of  a  Schulz  turbine.  No 
provision  is  here  made  for  enlarged  spaces,  but  the  neces- 
sary throttling  is  accomplished  by  the  great  length  of  the 
labvrinth  path.  The  designer  hoped  to  limit  his  clearance 
to  1  mm.  (0.039  in.).  The  outer  box  is  made  in  two  parts. 


FIG.  242 


Fig.  241  shows  a  stuffing,  box  by  the  same  designer,  built 
of  rings,  in  which  the  inner  rings  are  loose,  but  are  made 
with  a  neat  fit. 

The  Rateau  stuffing  box  is  shown  in  Fig.  242.  The 
main  part  consists  of  the  shaft,  a,  enclosed  by  a  close  fit- 
ting box  b,  of  suitable  metal.  The  steam  leaking  through 
this  space  flows  into  chamber  c,  where  a  constant  pressure 
of  about  12  Ibs.  absolute  is  maintained  by  a  reducing  valve. 
From  the  valve  the  steam  is  led  to  a  condenser.  Chamber 
c,  is  kept  steam  tight  from  the  outside  by  two  bronze  rings 


16  Steam  Engineering 

d,  d,  each  made  in  three  parts,  which  are  held  against  the 
shaft  with  slight  pressure  by  the  spiral  springs  e.  A  pres- 
sure in  an  axial  direction  is  caused  by  springs  f.  The 
chambers  of  all  the  stuffing  boxes  of  the  turbine  are  con- 
nected together.  Thus  a  portion  of  the  steam  that  leaves 
the  high  pressure  chamber  will  be  drawn  into  the  low  pres- 
sure side.  When  running  light,  partial  vacuum  exists  in 
all  the  stuffing  boxes,  the  reducing  valve  allowing  live 


FIG.  243 

steam  to  enter,  thus  preventing  air  from  being  drawn  in. 

Steam  is  led  in  Figs.  240  and  241  through  the  ring 
passages,  and  excludes  thereby  the  air,  so  that  the  vacuum 
does  not  suffer. 

The  construction  of  a  turbine  stuffing  box  as  steam  tight 
as  that  of  the  steam  engine  is  still  an  unsolved  problem. 
For  this  reason  we  might  add  the  excellent  stuffing  box  of 
Schwabe,  that  is  used  in  steam-engine  work,  shown  in 
Fig.  243.  This  consists  of  a  large  number  of  rings  D 


Regulation  17 

made  in  three  parts,  held  together  by  a  circumferential 
spiral  spring.  These  rings  (for  the  steam  engine)  press 
on  one  another,  and  should  either  not  touch  the  shaft  at 
all,  or  with  only  the  slightest  pressure.  With  turbines,  the 
soft  packing  at  the  outer  end  will  of  course  be  omitted, 
and  the  rings  must  be  prevented  from  turning,  and  so  con- 
structed as  to  be  tight  against  either  pressure  or  vacuum. 
The  inside  and  outside  ends  of  the  box  are  provided  with 
means  for  oiling. 

The  Regulation  of  the  Steam  Turbine. — The  regulation 
in  the  majority  of  different  systems  is  acomplished  by  sim- 
ple throttling,  thus  decreasing,  at  the  very  beginning,  the 
available  work  of  the  steam,  and  consequently  the  economy 
of  the  turbine.  The  loss  is  measured  by  the  product  of  the 
increase  of  entropy  and  the  absolute  temperature  of  the 
exhaust  steam,  which  can  easily  be  determined  from  the 
entropy  tables. 

The  ideal  conditions  would  be  to  constantly  work  with  a 
full  initial  pressure,  and  to  make  all  cross-sections  of  steam 
passages  suitable  to  the  power  required.  Constructively, 
this  idea  is  most  easily  applicable  to  the  single  stage  im- 
pulse turbine,  in  which  the  nozzles  are  opened  or  closed  one 
after  another  by  means  of  a  regulator. 

The  following  description  of  the  construction,  and  prin- 
ciples controlling  the  action  of  the  leading  types  of  steam 
turbines  manufactured  in  the  United  States  is  presented, 
with  the  hope  that  it  may  prove  to  be  not  only  interesting, 
but  instructive  as  well,  to  the  student. 

It  may  be  said  in  general  of  the  steam  turbine,  that  it 
has  passed  the  experimental  stage,  and  has  come  to  the 
front  as  an  efficient  power  producer,  having  a  bright 
future  before  it.  It  has  solved  the  problem  of  using  super- 


18  Steam  Engineering 

heated  steam,  owing  to  the  absence  of  all  rubbing  pnrts 
exposed  to  the  steam.  This  permits  the  use  of  steam  of 
high  temperature,  thus  making  it  possible  to  realize  the 
advantages  of  economical  operation. 


The  Westinghouse-Parsons  Steam 
Turbine 

The  Westinghouse-Parsons  Steam  Turbine  operates  on 
both  impulse  and  reaction  principles,  and  by  a  system  of 
compounding,  which  will  be  explained  later  on,  the  peri- 
pheral velocity  of  the  machine  has  been  so  reduced  as  to 


FIG.  244 

bring  it  within  practical  limits,  while  at  the  same  time  the 
power  value  of  the  steam  is  utilized  to  a  high  degree  of 
efficiency. 

The  speed  of  the  Westinghouse-Parsons  turbine  varies 
from  about  750  K.  P.  M.  for  a  5,000  K.  W.  machine,  to 
3,600  E.  P.  M.  for  a  400  K.  W.  turbine. 

19 


20  Steam  Engineering 

The  Westinghouse-Parsons  turbine  is  fundamentally 
based  upon  the  invention  of  Mr.  Charles  A.  Parsons,  who, 
while  experimenting  with  a  reaction  turbine  constructed 
along  the  lines  of  Hero's  engine,  conceived  the  idea  of 
combining  the  two  principles,  reaction  and  impulse,  and 
also  of  causing  the  steam  to  flow  in  a  general  direction 
parallel  with  the  shaft  of  the  turbine.  This  principle  of 
parallel  flow  is  common  to  all  four  types  of  turbines,  but 
is  perhaps  more  prominent  in  the  Westinghouse-Parsons, 
and  less  so  in  the  De  Laval. 

Fig.  235  shows  a  general  view  of  four  Westinghouse- 
Parsons  steam  turbines,  and  Fig.  244  shows  a  600  H.  P. 
machine  with  the  upper  half  of  the  cylinder,  or  stator  as  it 
is  termed,  thrown  back  for  inspection.  Fig  245  is  a  sec- 
tional view  of  a  Westinghouse-Parsons  turbine,  and  it  will 
be  noticed  that  there  are  three  sections  or  drums,  gradually 
increasing  in  diameter  from  the  inlet  A,  to  the  third  and 
last  group  of  blades.  This  arrangement  may  be  likened 
in  some  measure  to  the  triple  compound  reciprocating 
engine. 

Fig.  246  shows  the  complete  revolving  part  of  a  3,000 
H.  P.  turbine.  Its  weight  is  28,000  Ibs.,  length  over  all 
19  feet  8  inches,  and  12  feet  3  inches  between  bearings; 
the  largest  diamater,  6  feet. 

By  reference  to  Fig.  244  it  will  be  seen  that  the  inside 
of  the  cylinder  is  studded  with  rows  of  small  stationary 
blades,  and  that  the  rotor  or  revolving  part  of  the  ma- 
chine is  also  fitted  with  rows  of  small  blades,  similar  in 
shape  and  dimensions  to  the  stationary  blades.  When  the 
upper  half  of  the  cylinder  is  in  position,  each  row  of  sta- 
tionary blades  fits  in  between  two  corresponding  rows  of 
moving  blades.  This  arrangement  may  perhaps  be  better 


Westinglwusc-P  arsons  Turbine 


21 


FIG.  245 
SECTION  OF  STANDARD  WESTINGHOUSE  SINGLE  FLOW  TURBINE 


22 


Steam  Engineering 


understood  by  reference  to  Fig.  247,  which  illustrates  the 
relation  of  the  stationary  blades  to  the  moving  blades  when 
in  position,  and  also  shows  by  the  arrows  the  course  of  the 
steam  and  its  change  of  direction  caused  by  the  stationary 
blades. 

For  the  purpose  of  explanation  the  moving  blades  or 
vanes  may  be  considered  as  small  curved  paddles  pro- 
jecting from  the  surface  of  the  rotor,  and  there  is  a  large 
number  of  them,  as  for  instance,  taking  a  400  K.  W.  ma- 
chine, there  are  16,095  moving  blades  and  14,978  sta- 
tionary blades,  a  total  of  31,073. 


FIG.  246 

The  stationary  vanes,  as  previously  explained  project 
from  the  inside  surface  of  the  cylinder.  Both  stationary 
and  moving  vanes  are  similar  in  shape,  and  are  made  of 
hard  drawn  material,  and  they  are  set  into  their  places 
and  secured  by  a  caulking  process.  The  blades  vary  in  size 
from  y2  to  7  in.  in  length,  according  to  where  they  are 
used.  Referring  to  Fig.  24-4,  it  will  be  observed  that  the 
shortest  blades  are  placed  at  what  might  be  termed  the 
steam  end  of  each  section  or  drum  of  the  rotor  and  cylinder, 
and  that  their  length  gradually  increases,  corresponding 


Westing  house-Parsons  Turbine  23 

with  the  increased  volume  of  steam,  until  a  mechanical 
limit  is  reached,  when  a  new  group  of  blades  begins  on  a 
succeeding  drum  of  larger  diameter.  Eeferring  to  Fig. 
24:7,  which  is  a  sectional  view  of  four  rows  of  blades,  it  will 
be  noticed  that  all  the  blades,  whether  stationary  or  mov- 
ing, have  the  same  curvature.  Also  that  the  curves  are  set 
opposite  each  other.  The  reason  for  this  will  be  apparent 
as  the  diagram  is  studied.  The  steam  at  pressure  P  first 
comes  in  contact  with  row  1  of  stationary  blades.  It 
expands  through  this  row,  and  in  expanding  the  pressure 
falls  to  P'. 


STATIONARY  BLADES 

MOVING  BLADES 


3 


4 


J  J  »  D  B  . 


STATIONARY  BLADES 


'ING  BLADES 


FIG.  247 

The  energy  in  the  steam  is  converted  into  velocity,  and 
it  impinges  upon  row  2  of  moving  blades,  driving  them 
around  in  their  course  by  impulse.  A  second  expansion 
now  occurs  in  row  2,  and  again  the  energy  is  converted  into 
velocity,  but  this  time  the  reaction  of  the  steam  as  it  leaves 
the  blades  of  row  2  also  tends  to  impel  them  around  in 
their  course.  The  moving  blades  thus  receive  motion  from 
two  causes — the  one  due  to  the  impulse  of  the  steam  strik- 
ing them,  and  the  other  due  to  the  reaction  of  the  steam 
leaving  them. 


24  Steam  Engineering 

This  cycle  is  repeated  in  rows  3  and  4,  and  so  on  through- 
out the  length  of  the  rotor  until  the  exhaust  end  is  reached. 

It  should  be  noted  that  the  general  direction  taken  by 
the  steam  in  its  passage  through  the  turbine  is  in  the  form 
of  a  spiral  or  screw  line  about  the  rotor.  The  clearance 
between  the  blades  as  they  stand  in  the  rows  is  %  in.  for 
the  smallest  size  blades  and  %  in.  f°r  the  larger  ones, 
gradually  increasing  from  the  inlet  to  the  exhaust.  In  the 
5,000  K.  W.  machine  the  clearance  at  the  exhaust  end  be- 
tween the  rows  of  blades  is  1  in.  It  will  thus  be  seen  that 
there  is  ample  mechanical  clearance,  also  allowance  for 
lateral  motion  for  adjustment  of  the  rotor,  although  this  is 
very  slight,  as  the  rotor  is  balanced  at  all  loads  and  pres- 
sures by  the  balancing  pistons  PPP,  Fig.  245,  to  which 
reference  is  now  made.  These  pistons  revolve  within  the 
cylinder,  but  do  not  come  in  mechanical  contact  with  it; 
consequently  there  is  no  friction.  The  diameter  of  each 
piston  corresponds  to  the  diameter  of  one  of  the  three 
drums. 

The  steam  entering  the  chamber  A  through  valve  V 
presses  against  the  turbine  blades  and  goes  through  doing 
work  by  reason  of  its  velocity.  It  also  presses  equally  in 
the  opposite  direction  against  the  first  piston  P,  and  so 
the  shaft  or  rotor  has  no  end  thrust.  On  leaving  the  first 
group  of  blades  and  striking  the  second  group  the  pressure 
in  either  direction  is  again  equalized  by  the  balance  port 
E  allowing  the  steam  to  press  against  the  second  balance 
piston  P.  The  same  event  occurs  at  group  three,  the 
steam  acting  upon  the  third  piston  P. 

The  areas  of  the  balancing  pistons  are  such  that,  no 
matter  what  the  load  may  be,  or  what  the  steam  pressure 
or  exhaust  pressure  may  be,  the  correct  balance  is  main- 


Westinghouse-Parsons  Turl ine  25 

tained  and  there  is  practically  no  end  thrust.  Below  is 
shown  a  pipe  E  connecting  the  back  of  the  balancing  pis- 
tons with  the  exhaust  chamber.  This  arrangement  is  for 
the  purpose  of  equalizing  the  pressure  at  this  point  with 
the  pressure  in  the  exhaust  chamber. 

It  might  be  thought  that  the  blades,  on  account  of  their 
being  so  light  and  thin,  would  wear  out  very  fast,  but  ex- 
perience so  far  shows  that  they  do  not.  This  may  be  ac- 
counted for  in  two  ways.  First,  the  reduction  of  the 
velocity  of  the  steam,  the  highest  velocity  in  the  Parsons 
turbine  not  exceeding  600  ft.  per  second;  secondly,  the 
light  steam  thrust  on  each  blade,  said  to  be  equal  to  about 
1  oz.  avoirdupois.  This  is  far  within  the  bending  strength 
of  the  material.  A  steam  strainer  is  also  placed  in  the 
admission  port,  to  prevent  all  foreign  substances  from  en- 
tering the  turbine. 

A  rigid  shaft  and  thrust  or  adjustment  bearing  accu- 
rately preserves  the  clearances,  which  are  larger  in  +his 
turbine  than  in  other  types,  owing  to  the  fact  that  the 
entire  circumference  of  the  turbine  is  constantly  filled 
with  working  steam  when  in  operation. 

The  bearings  shown  in  Fig.  245  are  constructed  along 
lines  differing  from  those  of  the  ordinary  reciprocating 
engine.  The  bearing  proper  is  a  gun  metal  sleeve,  see  Fig. 
248,  that  is  prevented  from  turning  by  a  loose-fitting 
dowel.  Outside  of  this  sleeve  are  three  concentric  tubes 
having  a  small  clearance  between  them.  This  clearance  is 
kept  constantly  filled  with  oil  supplied  under  light  pres- 
sure, which  permits  a  vibration  of  the  inner  shell  or  sleeve 
and  at  the  same  time  tends  to  restrain  or  cushion  it.  This 
arrangement  allows  the  shaft  to  revolve  about  its  axis  of 
gravity,  instead  of  the  geometrical  axis,  as  would  be  the 


26 


Steam  Engineering 


case  if  the  bearing  were  of  the  ordinary  construction.  The 
journal  is  thus  to  a  certain  degree  a  floating  journal,  free 
to  run  slightly  eccentric  according  as  the  shaft  may  hap- 
pen to  be  out  of  balance. 


FIG.  248 

A  flexible  coupling  is  provided,  by  means  of  which  the 
power  of  the  turbine  is  transmitted  to  the  dynamo  or  other 
machine  it  is  intended  to  run.  The  oil  from  all  the  bear- 


Westinghouse-P  arsons  Turbine  27 

ings  drains  back  into  a  reservoir,  and  from  there  it  is  forced 
up  into  a  chamber,  where  it  forms  a  static  head,  which 
gives  a  constant  pressure  of  oil  on  all  the  bearings.  A 
secondary  valve  is  located  at  Vs,  by  means  of  which  high 
pressure  steam  may  be  admitted  to  the  steam  space  E  on 
the  same  principle  that  high  pressure  steam  is  admitted  to 
the  low  pressure  cylinder  of  a  compound  engine.  This 
valve  opens  automatically  in  cases  of  emergency,  such  as 
overload,  failure  of  the  condenser  to  work,  etc. 

The  shaft,  where  it  passes  through  either  cylinder  head, 
is  packed  with  a  water  seal  packing,  consisting  of  a  small 
paddle  wheel  attached  to  the  shaft,  which,  through  centri- 
fugal action,  maintains  a  static  pressure  of  about  5  Ibs.  per 
sq.  in.  in  the  water  seal,  thus  preventing  all  leakage  while 
at  the  same  time  it  is  frictionless. 

Governor. — The  speed  of  the  Westinghouse-Parsons  tur- 
bine is  regulated  by  a  fly  ball  governor  constructed  in  such 
manner  that  a  very  slight  movement  of  the  balls  serves  to 
produce  the  required  change  in  the  supply  of  steam.  Fig. 
249  is  a  diagram  of  the  governor  mechanism.  The  ball 
levers  swing  on  knife  edges  instead  of  pins.  The  gover- 
nor works  both  ways,  that  is  to  say,  when  the  levers  are 
oscillating  about  their  mid  position  a  head  of  steam  corre- 
sponding to  full  load  is  being  admitted  to  the  turbine,  and 
a  movement  from  this  point,  either  up  or  down,  tends  to 
increase  or  to  decrease  the  supply  of  steam. 

Referring  to  Fig.  249,  B  is  a  piston  directly  connected 
to  the  admission  valve.  Steam  is  admitted  to  this  piston 
under  control  of  the  pilot  valve  A,  which  has  a  slight  but 
continuous  reciprocating  motion  derived  from  the  eccentric 
rod  C,  and  the  function  of  the  governor  is  to  vary  the  plane 
of  oscillation  of  this  valve,  thus  causing  it  to  admit  more 


28  Steam  Engineering 

or  less  steam  to  piston  B.  The  admission  valve,  being 
actuated  exclusively  by  piston  B,  is  thus  caused  to  remain 
open  for  a  longer  or  shorter  period  of  time,  according  to 
the  load  upon  the  turbine. 

The  vibrations  of  the  admission  valve,  although  very 
slight,  are  continuous  and  regular,  about  165  per  minute, 
and  are  transmitted  primarily  by  means  of  an  eccentric, 
the  rod  of  which  is  shown  at  C,  Fig.  249. 


FIG.  249 

The  governor  sleeve  is  used  as  a  floating  fulcrum,  and 
the  points  D  and  E  are  fixed.  By  means  of  this  very 
ingenious  device  the  steam  is  admitted  to  the  turbine  in 
puffs,  either  long  or  short,  according  to  the  demand  for 
steam.  At  full  load  the  puffs  merge  into  an  almost  con- 
tinuous blast.  "When  the  load  has  increased  to  the  point 
where  the  valve  is  wide  open  continuously,  a  full  head  of 
steam  is  being  admitted.  Beyond  this  the  secondary  valve 
comes  into  action,  thus  keeping  the  speed  up  to  normal. 


Westinghouse-Parsons  Turbine  29 

The  rotor  requires  perfect  balancing  to  insure  quiet 
running,  but  this  is  easily  accomplished  in  the  shop  by 
means  of  a  balancing  machine  used  by  the  builders. 

Steam  turbines  generally  show  higher  efficiency  in  the 
use  of  steam  than  reciprocating  engines  do,  and  this  fact 
is  due  to  three  leading  causes.  First,  it  is  possible  with 
the  turbine  to  use  highly  superheated  steam  which,  owing 
to  the  difficulties  attending  lubrication,  could  not  be  used 
in  the  reciprocating  engine.  Second,  a  larger  proportion  of 
the  heat  contained  in  the  steam  is  converted  into  work,  for 


FIG.  250 
NEW  BLADING  MATERIAL 

the  reason  that  the  steam  is  allowed  to  expand  to  a  much 
lower  pressure,  and  into  a  higher  vacuum.  In  addition  to 
this,  the  velocity  of  the  expanding  steam  is  utilized  in  a 
much  higher  degree  in  the  turbine  as  compared  with  the  re- 
ciprocating engine.  Third,  mechanical  friction  or  lost 
work  is  reduced  to  the  minimum.  Under  test  a  400  K.  W. 
Westinghouse-Parsons  steam  turbine,  using  steam  at  150 
Ibs.  initial  pressure  and  superheated  about  180°,  consumed 
11.17  Ibs.  of  steam  per  brake  horse  power  hour  at  full  load. 
The  speed  was  3,550  R.  P.  M.  and  the  vacuum  was  28  in. 


30  Steam  Engineering 

With  dry  saturated  steam  the  consumption  was  13.5  Ibs. 
per  B.  H.  P.  hour  at  full  load,  and  15.5  Ibs.  at  one-half 
load. 

A  1,000  K.  W.  machine,  using  steam  of  150  Ibs.  pres- 
sure and  superheated  140°,  exhausting  into  a  vacuum  of 
28  in.,  showed  the  very  remarkable  economy  of  12.66  Ibs 
of  steam  per  E.  H.  P.  per  hour. 

A  1,500  K.  W.  Westinghouse-Parsons  turbine,  using  dry 
saturated  steam  of  150  Ibs.  pressure  with  27  in.  vacuum, 
consumed  14.8  Ibs.  steam  per  E.  H.  P.  hour  at  full  load, 
and  17.2  Ibs.  at  one-half  load. 

The  Westinghouse  machine  company  have  recently  in- 
troduced a  new  blade  material  which  is  now  used  in  all 
Westinghouse  turbines.  It  is  a  copper-coated  steel  blade, 
or,  as  designated  by  the  builder,  "Monnot  metal."  in  which 
the  copper  coating  (seen  in  Fig.  250)  is  chemically  welded 
to  the  steel  so  thoroughly  that  the  blades  can  be  drawn  to 
the  desired  shape  from  the  original  ingot,  without  weaken- 
ing the  union  between  the  copper  and  steel.  The  process 
of  drawing  makes  the  copper  coating  somewhat  thicker  at 
the  inlet  and  outlet  edges  of  the  blade,  though  the  remain- 
ing portions  of  the  blade  surfaces  are  coated  with  an  abso- 
lutely uniform  thickness  of  copper.  The  only  portion  of 
the  blade  where  steel  is  exposed,  is  the  small  surface  of  the 
tip  of  the  blade  where,  however,  corrosion  is  the  least  detri- 
mental, for  should  the  tips  corrode,  the  copper  coating 
would  still  remain  intact,  thus  leaving  the  working  blade 
surfaces  untouched  and  the  blade  clearances  unaltered. 

Figs.  251  and  252  show  sectional  elevations  of  the  double 
flow  type  of  steam  turbines  now  being  manufactured  by  the 
Westinghouse  company,  in  addition  to  the  standard  single 
flow  turbine  already  described. 


Westinghoitse-Parsons  Turbine 


31 


FIG.  251 
SECTION  OF  WESTINGITOrSE  DOUBLE  FLOW  TURBINE 


32 


Steam  Engineering 


FIG.  252 

WESTINGHOUSE  DOUBLE  FLOW  LOW-PRESSURE  TURBINE 
Sectional  Elevation 

Fig.  251  shows  the  machine  as  adapted  for  using  steam 
of  high  initial  pressure,  in  fact  an  impulse  turbine,  in  which 
the  steam  admitted  first  to  the  nozzle  block,  is  expanded 


Westinghouse-Parsons  Turbine  33 

in  nozzles  arranged  about  the  periphery,  and  impinges 
upon  the  impulse  buckets  of  the  central  rotation  wheel. 
There  are  two  rows  of  moving  blades  upon  the  impulse 
wheel,  with  an  intermediate  set  of  reversing  blades  as 
shown.  Issuing  from  the  delivery  side  of  this  wheel  with 
its  velocity  energy  practically  all  abstracted,  the  steam 
passes,  as  shown  by  the  arrow,  to  an  intermediate  set  of 
Parsons  blading.  As  this  blading  has  no  counterpart  upon 
the  other  side  of  the  turbine,  the  pressure  upon  it  must  be 
counterbalanced,  and  this  is  done  by  making  the  extension 
of  the  hub  by  which  the  impulse  wheel  is  keyed  to  the  shaft, 
into  a  piston  or  dummy  of  the  mean  diameter  of  the  inter- 
mediate stage,  as  shown  at  P.  After  passing  the  inter- 
mediate stage  the  steam  divides,  one  portion  passing 
directly  to  the  low-pressure  blading  at  the  left,  while  the 
rest  passes  through  the  hollow  shell  of  the  rotor  to  the 
similar  pressure  blades  upon  the  right.  As  these  sections 
are  equal  and  symmetrical  they  counterbalance  each  other, 
so  that  no  further  dummies  are  required  than  the  small 
one  already  referred  to. 

For  regulating  the  steam  supply  in  accordance  with  the 
load,  two  methods  other  than  that  of  simple  throttling  with 
its  sacrifice  of  temperature  head  are  available. 

The  admission  area  may  be  varied  by  the  cutting  in  and 
out  of  nozzles. 

The  duration  of  the  time  of  admission  through  a  con- 
stant area  may  be  varied. 

The  first  is  the  Curtis  method,  impracticable  for  a  full- 
admission  turbine  like  the  Parsons ;  the  second,  that  which 
has  been  developed  by  the  Westinghouse  engineers  for  the 
Parsons  as  they  build  it.  The  adoption  of  the  partial  ad- 
mission for  first  stage  in  the  double  flow  machine  gave  the 


34  Steam  Engineering 

Westinghouse  designers  their  option  of  the  two  method*5, 
but  they  have  preferred  to  continue  the  variable  dura  I  ion 
puff  system,  already  described  in  connection  with  single 
flow  machines.  A  disadvantage  of  the  variable  nozzle 
method  of  regulation  is,  that  if  the  area  of  the  nozzles  of 
the  succeeding  stages  is  correctly  proportioned  to  pass 
along  the  steam  admitted  by  a  certain  number  of  primary 
nozzles,  it  will  be  too  great  when  fewer  nozzle*  are  in 
action,  and  too  small  when  there  are  more.  This  will 
result  in  a  considerable  variation  of  the  pressure  in  the 
succeeding  stages,  and  of  the  pressure  ratios  of  expansion 
and  jet  velocity  acquired  in  those  stages,  and  interfere 
with  the  designer's  intention  with  regard  to  the  distribu- 
tion of  work  and  the  relation  of  blade  to  jet  velocity.  This 
could  be  overcome  only  by  adjusting  the  nozzles  of  the  suc- 
ceeding individual  stages  in  harmony  with  those  of  the 
initial  stage. 

If,  on  the  other  hand,  the  passages  through  the  turbine 
are  permanently  arranged  in  the  correct  relation  to  each 
other,  this  relation  will  persist  whether  the  How  is  con- 
tinuous or  intermittent,  and  the  energy  developed  can  be 
regulated  to  the  demand  by  making  the  flow  more  nearly 
continuous,  as  the  load  approaches  the  rated  capacity  of 
the  machine.  So  far  as  the  change  in  initial  pressure  due 
to  the  alternate  letting  on  and  shutting  off  of  the  steam  is 
concerned,  theory  indicates,  and  experiment  proves  that 
where  the  expansion  in  each  stage  is  but  a  small  part  of 
the  total  range,  as  in  the  Parsons  turbine,  the  initial  and 
terminal  pressures  of  each  stage  rise  and  fall,  resulting  in 
a  fairly  constant  pressure  ratio  at  each  successive  expan- 
sion; in  other  words,  for  small  ranges,  and  throttle  gov- 
erning, the  nozzle  and  blade  areas  are  reasonably  correct 


Westingliouse-Parsons  Turbine  35 

through  a  wide  range  of  load  and  pressure  distribution. 
For  this  reason  the  impulse  section  of  the  Westinghouse 
turbine,  doing,  say,  only  one-fifth  of  the  total  work,  is 
properly  proportioned  for  a  wide  range  in  load  and  may  be 
governed  without  resorting  to  intermediate  nozzle  control, 
and  without  sacrifice  of  economy  and  fractional  loads. 

Advantage  Gained. — The  balancing  pistons  have  been  re- 
duced to  a  minimum.  In  the  single-flow  types  the  high- 
pressure  dummy  occupies  fully  one-half  of  the  total  dummy 
piston  length  on  the  shaft,  while  the  low-pressure  piston 
is  2y2  times  the  high-pressure  diameter. 

A  reduction  of  nearly  50  per  cent  in  shaft  span  between 
bearings.  Owing  to  the  rotor  construction  a  better  loading 
of  the  shaft  is  also  obtained;  that  is,  the  rotor  weight  is 
transmitted  to  the  shaft  at  points  nearer  the  bearings  than 
in  the  single-flow  rotor,  where  the  weight  is  largely  dis- 
tributed. 

An  increase  to  about  double  rotative  speed  made  possible 
by  the  reduction  in  shaft  span,  and  loading;  that  is,  to  a 
general  greater  rigidity  of  the  double-flow  construction. 

A  reduction  of  about  70  per  cent  in  the  bulk  of  the  main 
parts  of  the  machine  with  practically  the  same  output. 

Internal  cylinder  stresses  due  to  high-pressure  and  high- 
temperature  steam  are  avoided  by  isolating  the  incoming 
steam  within  separate  nozzle  chambers,  so  that  the  main 
body  of  the  turbine  is  subjected  to  steam  having  not  much 
over  75  pounds  gauge  pressure  with  practically  no  super- 
heat. 

The  bulk  of  the  low-pressure  stage  is  better  distributed 
and  the  length  of  the  low-pressure  blades  greatly  reduced 
by  subdividing  this  stage  into  two  parts  located  at  opposite 
ends  of  the  rotor. 

As  will  be  plain  from  what  has  preceded,  the  advantages 


36 


Rieam  Engineering 


sought  in  this  form  of  turbine  are  constructional  and  me- 
chanical rather  than  economic.  For  high-pressure  work 
the  standard  Westinghouse-Parsons  single-flow  turbine  will 
be  built  up  to  capacities  of  3,000  kilowatts;  above  5,000 
kilowatts  all  units  will  be  built  upon  the  double-flow  prin- 


FIG.  253 
3,000  K.  W.  WESTINGHOUSE  DOUBLE  FLOW  STEAM  TURBINE 

ciple.  The  latter  construction  will  also  be  used  for  the 
low-pressure  turbines  to  which  it  is  so  admirably  adapted, 
as  shown  in  Fig.  252,  which  is  a  section  of  the  Westing- 
house  low-pressure,  double-flow,  steam  turbine  designed 
for  utilizing  the  exhaust  steam4  from  non-condensing  recip- 
rocating engines.  Fig.  253* shows  a  view  of  a  double-flow 
steam  turbine  without  the  generator  attached. 


UNIVERSITY 

OF 


The  Curtis  Steam  Turbine 

In  the  Curtis  turbine  the  heat  energy  in  the  steam  is 
imparted  to  the  wheel,  both  by  impulse  and  reaction,  but 
the  method  of  admission  differs  from  that  of  the  Westing- 
house-Parsons,  in  that  the  steam  is  admitted  through  ex- 
panding nozzles  in  which  nearly  all  of  the  expansive  force 
of  the  steam  is  transformed  into  the  force  of  velocity.  The 
steam  is  caused  to  pass  through  one,  two,  or  more  stages 
of  moving  elements,  each  stage  having  its  own  set  of  ex- 
panding nozzles,  each  succeeding  set  of  nozzles  being  greater 
in  number  and  of  larger  area  than  the  preceding  set.  The 
ratio  of  expansion  within  these  nozzles  depends  upon  the 
number  of  stages,  as,  for  instance,  in  a  two-stage  machine, 
the  steam  enters  the  initial  set  of  nozzles  at  boiler  pres- 
sure, say  180  Ibs.  It  leaves  these  nozzles  and  enters  the 
first  set  of  moving  blades  at  a  pressure  of  about  15  Ibs., 
from  which  it  further  expands  to  atmospheric  pressure  in 
passing  through  the  wheels  and  intermediates.  From  the 
pressure  in  the  first  stage  the  steam  again  expands  through 
the  larger  area  of  the  second  stage  nozzle  to  a  pressure 
slightly  greater  than  the  condenser  vacuum  at  the  entrance 
to  the  second  set  of  moving  blades,  against  which  it  now 
impinges,  and  passes  through  still  doing  work,  due  to 
velocity  and  mass. 

From  this  stage  the  steam  passes  to  the  condenser.  If 
the  turbine  is  a  four-stage  machine  and  the  initial  pressure 
is  180  Ibs.,  the  pressure  at  the  different  stages  would  be  dis- 
tributed in  about  the  following  manner :  Initial  pressure, 
180  Ibs.;  first  stage,  50  Ibs.;  second  stage,  5  Ibs.;  third 

37 


38 


Steam  Engineering 


stage,  partial  vacuum,  and  fourth  stage,  condenser  vacuum. 

Fig.  254  gives  a  general  view  of  a  5,000  K.  W.  turbine 

and  generator.     The  generator  is  shown  at  the  top,  while 

the  turbine  occupies  the  middle  and  lower  section.    A  por- 


FIG.  254 

5,000  K.  W.  CURTIS  STEAM  TURBINE  DIRECT  CONNECTED  TO  5.000  K.  W. 
THREE-PHASE  ALTERNATING  CURRENT  GENERATOR 

tion  of  the  inlet  steaml  pipe  is  shown,  ending  in  one  nozzle 
group  at  the  side.  There  are  three  groups  of  initial  noz- 
zles, two  of  which  are  not  shown.  The  revolving  parts  of 
this  unit  are  set  upon  a  vertical  shaft,  the  diameter  of  the 


The  Curtis  Turbine  ,  39 

shaft  corresponding  to  the  size  of  the  unit.  For  a  machine 
having  the  capacity  of  the  one  illustrated  by  Fig.  254  the 
diameter  of  the  shaft  is  14  in. 

The  shaft  is  supported  by,  and  runs  upon  a  step  bearing 
at  the  bottom.  This  step  bearing  consists  of  two  cylindrical 
cast  iron  plates,  bearing  upon  each  other  and  having  a 
central  recess  between  them  into  which  lubricating  oil  is 
forced  under  pressure  by  a  steam  or  electrically  driven 
pump,  the  oil  passing  up  from  beneath.  A  weighted  ac- 
cumulator is  sometimes  installed  in  connection  with  the 
oil  pipe  as  a  convenient  device  for  governing  the  step  bear- 
ing pumps,  and  also  as  a  safety  device  in  case  the  pumps 
should  fail,  but  it  is  seldom  required  for  the  latter  pur- 
pose, as  the  step  bearing  pumps  have  proven,  after  a  long 
service  in  a  number  of  cases,  to  be  reliable.  The  vertical 
shaft  is  also  held  in  place  and  kept  steady  by  three  sleeve 
bearings,  one  just  above  the  step,  one  between  the  turbine 
and  generator,  and  the  other  near  the  top.  These  guide 
bearings  are  lubricated  by  a  standard  gravity  feed  system. 
It  is  apparent  that  the  amount  of  friction  in  the  machine 
is  very  small,  and  as  there  is  no  end  thrust  caused  by  the 
action  of  the  steam,  the  relation  between  the  revolving  and 
stationary  blades  may  be  maintained  accurately.  As  a  con- 
sequence, therefore,  the  clearances  are  reduced  to  the  mini- 
mum. 

The  Curtis  turbine  is  divided  into  two  or  more  stages, 
and  each  stage  has  one,  two  or  more  sets  of  revolving 
blades  bolted  upon  the  peripheries  of  wheels  keyed  to  the 
shaft.  There  are  also  the  corresponding  sets  of  stationary 
blades,  bolted  to  the  inner  walls  of  the  cylinder  or  casing. 
As  in  the  Westinghouse-Parsons  type,  the  function  of  the 
stationary  blades  is  to  give  direction  to  the  flow  of  steam. 


40 


Steam  Engineering 


Fig.  255  illustrates  one  stage  of  a  500  K.  W.  turbine  in 
course  of  construction.  It  will  be  observed  that  there  are 
three  wheels,  and  that  in  the  spaces  between  these  wheels 
the  stationary  buckets  or  vanes  are  placed,  being  firmly 
bolted  to  the  casing.  Fig.  256  shows  sections  of  both 
revolving  and  stationary  buckets  ready  to  be  placed  in 


FIG,  255 
500  K.  W.  CUBTIS  STEAM  TURBINE  IN  COUBSE  OF  CONSTRUCTION 

position.  The  illustration  in  Fig.  255  shows  the  lower  or 
last  stage.  The  clearance  between  the  revolving  and  sta- 
tionary blades  is  from  -fa  to  TV  in.,  thus  reducing  the 
wasteage  of  steam  to  a  very  low  percentage.  The  diameters 
of  the  wheels  vary  according  to  the  size  of  the  turbine, 
that  of  a  5,000  K.  W.  machine  being  13  ft. 


The  Curtis  Turbine 


41 


REVOLVING   BUCKETS   FOR   CURTIS    STEAM    TURBINE 


STATIONARY  BUCKETS  P'OR  CURTIS   STEAM  TURBINE 

FIG.  256 


Fig.  257  shows  a  nozzle  diaphragm  with  its  various 
openings,  and  it  will  be  noted  that  the  nozzles  are  set  at 
an  angle  to  the  plane  of  revolution  of  the  wheel. 


42 


Steam  Engineering 


Fig.  258  is  a  diagram  of  the  nozzles,  moving  blades  and 
stationary  blades  of  a  two-stage  Curtis  steam  turbine.  The 
steam  enters  the  nozzle  openings  at  the  top,  controlled  by 


cccccccccccccccccccccc 


ll\\ 


FIG.  258 
DIAGRAM  OF  NOZZLES  AND  BUCKETS  IN  CURTIS  STEAM  TURBINE 

the  valves  shown,  the  regulation  of  which  will  be  explained 
later  on.  In  the  cut  Fig.  258  two  of  the  valves  are  open, 
and  the  course  of  the  steam  through  the  first  stage  is  indi- 


The  Curtis  Turbine  43 

cated  by  the  arrows.  After  passing  successively  through 
the  different  sets  of  moving  blades  and  stationary  blades 
in  the  first  stage,  the  steam  passes  into  the  second  steam 
chest.  The  flow  of  steam  from  this  chamber  to  the  second 
stage  of  buckets  is  also  controlled  by  valves,  but  the  func- 
tion of  these  valves  is  not  in  the  line  of  speed  regulation, 
but  for  the  purpose  of  limiting  the  pressure  in  the  stage 
chambers,  in  a  manner  somewhat  similar  to  the  control  of 
the  receiver  pressure  in  a  two-cylinder  or  three-cylinder 
compound  reciprocating  engine. 

The  valves  controlling  the  admission  of  steam  to  the 
second,  and  later  stages  differ  from  those  in  the  first  group 
in  that  tl.ey  partake  more  of  the  nature  of  slide  valves  and 
may  be  operated  either  by  hand,  or  automatically ;  in  fact, 
they  require  but  very  little  regulation,  as  the  governing 
is  always  done  by  the  live  steam  admission  valves. 

Action  of  the  Steam  in  a  Two-stage  Machine. — As  prev- 
iously stated,  the  steam  first  strikes  the  moving  blades  in 
the  first  stage  of  a  two-stage  machine  at  a  pressure  of  about 
15  Ibs.  above  atmospheric  pressure,  but  with  great  velocity. 
From  this  wheel  it  passes  to  the  set  of  stationary  blades 
between  it  and  the  next  lower  wheel.  These  stationary 
blades  change  the  direction  of  flow,  of  the  steam  and  cause 
it  to  impinge  the  buckets  of  the  second  wheel  at  the  proper 
angle. 

This  cycle  is  repeated  until  the  steam  passes  from  the 
first  stage  into  the  receiving  chamber,  or  steam  chest  for  the 
second  stage.  Its  passage  from  this  chamber  into  the 
second  stage  is  controlled  by  valves,  which,  as  before  stated, 
a  iv  regulated  either  by  hand,  or  automatically.  The  course 
of  the  steam  through  the  nozzles  and  blades  of  the  second 
stage  is  clearly  indicated  by  the  arrows,  and  it  will  be 
noted  that  steam  is  passing  through  all  the  nozzles. 


44    .  Steam  Engineering 

At  this  point  it  might  be  well  to  consider  the  question 
which  no  doubt  arises  in  the  mind  of  the  student  in  his 
efforts  to  grasp  the  underlying  principles  in  the  action  of 
the  steam  turbine.  Why  is  it  that  the  impingement  of  the 
steam,  at  so  low  a  pressure,  against  the  blades  or  buckets 
of  the  turbine,  imparts  such  a  large  amount  of  energy 
to  the  shaft? 

The  answer  is,  because  of  velocity,  and  a  good  example 
of  the  manner  in  which  velocity  may  be  made  to  increase 
the  capacity  of  an  agent  to  do  work  is  illustrated  in  the 
following  way :  Suppose  that  a  man  is  standing  within 
arm's  length  of  a  heavy  plate  glass  window  and  that  he 
holds  in  his  hand  an  iron  ball  weighing  10  Ibs.  Suppose 
the  man  should  place  the  ball  against  the  glass  and  press 
the  same  there  with  all  the  energy  he  is  capable  of  exerting. 
He  would  make  very  little,  if  any,  impression  upon  the 
glass.  But  suppose  that  he  should  walk  away  from  the 
window  a  distance  of  20  ft,  and  then  exert  the  same  amount 
of  energy  in  throwing  the  ball  against  the  glass,  a  different 
result  would  ensue.  The  velocity  with  which  the  ball  wouW 
impinge  the  surface  of  the  glass  would  no  doubt  ruin  the 
window.  Now,  notwithstanding  the  fact  that  weight,  energy 
and  time  involved  were  exactly  the  same  in  both  instances, 
yet  a  much  larger  amount  of  work  was  performed  in  the 
latter  case,  owing  to  the  added  force  imparted  to  the  ball 
by  the  velocity  with  which  it  impinged  against  the  glass. 

Speed  Regulation. — The  governing  of  speed  is  accom- 
plished in  the  first  set  of  nozzles,  and  the  control  of  the 
admission  valves  here  is  effected  by  means  of  a  centrifugal 
governor  attached  to  the  top  end  of  the  shaft,  This  gover- 
nor, by  a  very  slight  movement,  imparts  motion  to  levers, 
which  in  turn  work  the  valve  mechanism.  The  admission 


Tlic  Curd*  Tin-line 


45 


of  steam  to  the  nozzles  is  controlled  by  piston  valves,  which 
are  actuated  by  steam  from  small  pilot  valves  which  are  in 
turn  under  the  control  of  the  governor  Fig.  259  shows  the 


. 

FIG.  259 

GOVERNOR  FOR  5.000  K.   W.  TURBINE 

form  a  governor  for  a  5,000  K.  W.  turbine,  and  Fig.  260 
shows  the  electrically  operated  admission  valves  for  one 
set  of  nozzles. 


4-n 


Engineering 


Speed  regulation  is  affected  by  varying  the  number  of 
nozzles  in  flow,  that  is  for  light  loads  fewer  nozzles  are  open, 
and  a  smaller  volume  of  steam  is  admitted  to  the  turbine 
wheel,  but  the  steam  that  is  admitted  impinges  the  moving 
blades  with  the  same  velocity  always,  no  matter^  whether 
the  volume  be  large  or  small.  With  a  full  load  and  all  the 
nozzle  sections  in  flow,  the  steam  passes  to  the  wheel  in  a 
broad  belt  and  steady  flow. 


FIG.  200 
ELECTRICALLY  OPERATED  VALVE 

In  addition  to  the  method  just  described,  of  actuating 
the  addmission  valves  by  steam,  the  General  Electric  Com- 
pany, manufactures  of  the  Curtis  Turbine,  have  recently 
introduced  a  system  of  hydraulicaly  operated  valves  for 
speed  regulation. 

These  valves  are  also  of  the  poppet  type,  and  each  i? 
closed  by  a  helical  spring  in  compression.  In  the  closed 
position  they  are  held  tight  by  steam  pressure,  against 
which  they  are  openedi  The  valves  on  one  machine  are  all 


The  Curtis  Turbine 


•r 


duplicates,  and  are  opened  in  rotation  by  cams  (one  for 
each  valve)  mounted  on  a  shaft,  each  cam  being  given  in 
succession  an  angular  advance  over  its  predecessor.  This 


n  i  :i 


FIG.  261 

cam  shaft  is  rotated  by  the  piston  in  a  hydraulic  cylinder, 
the  cylinder  being  mounted  either  on  the  generator  or 
valve  casing. 


48  Steam  Engineering 

The  valves  open  gradually;  that  is  there  will  be  throt- 
tling on  the 'opening,  or  closing  valve,  before  the  next  one 
in  either  side  is  opened  or  closed,  so  that  the  exact  amount 
of  steam  required  can  be  admitted  for  any  definite  load. 
Fig.  261  shows  a  section  of  the  hydraulic  cylinder,  and 
controlling  valve.  The  position  of  piston  A  is  controlled 
by  a  balanced  piston  valve  B.  The  liquid  under  pressure 
is  admitted  at  C,  and  discharged  at  D.  The  rod  E  is  con- 
nected with  the  governor,  and  rod  F  with  the  piston  rod. 

Operation. — The  rod  E  receives  its  motion  from  the 
governor,  and  occupies  a  fixed  position  for  any  given  speed 
between  the  limits  through  which  the  governor  is  designed 
to  operate.  The  lever  arms  G  and  G',  and  H  and  H'  are 
so  proportioned  that  the  piston  A  will  occupy  a  definite 
fixed  position  to  correspond  with  any  position  of  rod  E. 

Therefore  as  the  crosshead  K  transmits  its  motion 
through  connecting  rod  N;  (see  Fig.  262)  to  the  crank 
L  on  the  cam  shaft  M,  there  will  be  a  fixed  number  of 
valves  open  for  any  position  of  the  governor.  While  the 
turbine  is  operating  at  a  fixed  speed,  the  piston  valve  will 
occupy  a  central  position,  closing  both  ports  0  and  P. 
When  there  is  a  drop  in  speed,  the  governor  causes  rod  E 
to  move  down,  thus  opening  part  0  to  discharge,  and  port 
P  to  admit  liquid  under  piston  A  which  them  moves  up- 
wards, opening  more  valves  to  satisfy  the  demand  for  steam. 
In  moving  up  the  piston  transmits  its  motion  through  rod 
F  to  the  piston  valve  B,  restoring  it  to  the  central  position. 
When  operating  on  a  fixed,  or  slightly  varying  load,  the 
main  piston  should  not  continuously  move  over  a  distance 
greater  than  that  corresponding  to  the  lap  of  the  piston 
valve,  and  under  no  condition  of  governing  should  the 
main  piston  continually  travel  back  and  forth  over  a  dis- 


The  Curtis  Turbine 


49 


FIG.  262 


tance  greater  than  this.     Any  larger  movements   should 
only  occur  when  greater  or  less  power  is  demanded  for 


50  Steam  Engineering 

considerable  variation  in  load.     Any  continuous  opening 
and  closing  of  the  valves  during  a  steady  load  is  an  indi 
cation  of  excessive  friction  in  the  governor  rigging,  or  pis- 
ton valve,  and  it  should  be  eliminated  as  soon  as  possible. 

It  is  essential  that  the  pistons  on  the  piston  valve  B, 
Fig.  261  be  reduced  in  diameter  at  their  centers  -^  in. 
as  indicated  in  the  illustration.  If  this  is  not  done  it  may 
be  responsible  for  sticking  of  the  piston  valve,  thereby  in- 
terfering with  the  satisfactory  regulation  of  the  machine. 

For  different  machines  the  connections  may  be  altered, 
and  in  some  the  operation  is  reversed,  by  crossing  the  ports, 
so  that  the  piston  A  will  move  in  the  same  direction  as  the 
piston  valve  B,  and.  in  the  application  of  the  gear  to  later 
machines  of  large  capacity,  it  has  been  found  advisable  to 
place  the  cylinder  horizontal,  operating  crank  shafts  of 
valve  casings  by  means  of  rack  and  pinion  with  bevel  gear 
transmission,  or  with  racks  operating  directly  on  pinions 
on  cam  shafts,,  but  the  principle  of  operation  is  the  same, 
only  modified  in  application  to  suit  particular  cases. 

Adjustment. — With  the  piston  A,  and  the  piston  valve 
B,  both  in  their  mid  positions,  the  rod  F  should  be  of  such 
a  length  that  the  lever  Gr  will  be  horizontal.  The  connect- 
ing rod  N  is  adjusted  so  that  with  piston  A  at  the  extreme 
end  of  its  up  stroke,  all  the  steam  valves  are  open,  and  the 
first  one  just  ready  to  close.  With  the  piston  A  in  this 
position  (i.  e.,  at  the  extreme  end  of  its  stroke,)  and  the 
governor  at  the  low  speed  position,  the  rod  E  should  be 
adjusted  so  that  the  piston  valve  B,  will  be  in  its  mid 
position. . 

Precautions. —  (1)  It  is  absolutely  essential  that  all  con- 
nections between  governor  and  valve  be  entirely  free  from 
friction. 


The  Curtis  Turbine  51 

(2)  The  piston  valve  B  must  move  freely  for  the  whole 
length  of  its  stroke,  so  that  if  the  rod  E  be  disconnected 
from  the  arm  G,  the  valve  will  drop  of  its  own  weight, 
either  with  pressure  on  or  off. 

(3)  There  must  be  absolutely  no  binding  at  any  of  the 
joints  through  the  whole  travel. 

(4)  The  liquid  used  must  be  entirely  free  from  dirt,  or 
grit,  of  any  nature. 

(5)  On  the  main  steam  valves;  in  the  closed  position, 
when  the  roller  has  ridden  off  of  the  cam,  it  must  not  press 
on  the  cam  shaft,  as  this  will  prevent  valve  seating  properly. 

(6)  The  piston  valve  and  bore  must  be  perfectly  round 
and   absolutely  straight,   or  an  excessive  leakage  will  be 
established  on  one  side  of  the  valve,  causing  it  to  bind. 

(7)  The  pressure  exerted  by  the  main  valve  springs  in 
the  open  position  must  be  in  excess  of  that  sufficient  to 
overcome  steam  pressure  on  rod,  and  any  friction  that  may 
exist  in  packing. 

(8)  The  plate  below  main  valve  springs  must  be  a  slid- 
ing fit  in  guides  at  all  temperatures. 

(9)  Care  must  be  taken  in  the  adjustment  of  the  length 
of  the  rods  E  and  F,  that  in  no  position  of  the  governor,  or 
piston,  can  the  piston  valve  become  jammed  at  the  end  of 
its  stroke. 

(10)  A  heavy  oil  must  not  be  used  or  the  action  will  be 
sluggish. 

Piping. — Fig.  263  shows  a  diagram  of  piping  for  a  ma- 
chine using  oil  to  operate  the  valves.  This  is  supplied  by  the 
same  pumps  that  furnish  lubrication  for  the  guide  bearings. 
A  relief  valve  E,  is  adjusted  to  the  desired  pressure  for 
operating  the  gear.  When  the  speed  is  constant  and  the 
valve  not  taking  any  oil,  the  excess  supplied  by  pumps  will 
be  discharged  through  this  relief  valve. 


52  Steam  Engineering 

The  special  reducing  valve  shown  in  Fig.  264,  and  at  S, 
Fig.  263,  is  provided  to  control  the  amount  of  oil  supplied 
to  the  bearings. 

This  valve  can  be  closed,  or  adjusted  over  a  wide  range,  by 
altering  the  effective  length  of  baffler. 

Referring  to  Fig.  263,  the  tank  marked  "air  chamber"  is 


fte/iefVatvf 


provided  in  order  to  give  a  reserved  capacity  of  oil  should 
the  pumps  for  any  reason  stop,  and  also  to  form  an  air 
cushion  on  the  system.  The  valve  at  the  top  of  this  tank 
should  be  kept  closed,  and  the  oil  allowed  to  compress  the 
air  contained  in  the  tank,  and  from  time  to  time  the  tank 
should  be  completely  emptied  and  refilled  with  air.  The 


The  Curtis  Turbine 


53 


emptying  can  be  easily  accomplished  by  opening  the  three- 
way  valve  to  discharge  to  the  oil  tank.  This  need  not  in- 
terfere with  the  operation  of  the  machine.  After  the  air 
chamber  is  emptied,  valve  J  should  be  closed,  and  the  three- 
way  valve  open  to  admit  oil  to  the  chamber. 


C 


FIG.  264 


In  installations  where  oil  is  used  for  the  turbine  step 
bearing,  oil  for  the  operating  gear  and  bearings  may  be 
taken  from  the  high  pressure  pipe  line,  on  the  pump  side 
of  the  step  baffler,  through  a  reducing  valve.  The  piping 


54 


Steam  Engineering 


system  remains  as  shown  diagramatically  in  Fig.  263  except 
for  change  in  source  of  supply  of  operating  fluid. 

In  case  the  station  installation  includes  an  air  compres- 


FIG.  265 


sor,  this  equalizing  tank  may  be  piped  in  the  system,  the 
connection  being  made  on  the  side  of  the  tank  (as  provided 
for).  The  refilling  of  the  tank  is  thus  much  simplified, 
and  its  capacity  for  emergency  operation  greatly  increased. 


The  Curtis  Turbine  55 

Care  should  be  taken  to  insure  tightness  of  both  valve  con- 
trolling air  supply  to  tank,  and  pet  cock  at  the  top. 

Step  Bearing. — Fig.  265  is  a  section  through  the  cast  iron 
step  blocks.  The  lower  block  in  the  illustration  has  two 
holes  drilled  in  it  to  match  the  two  dowel  pins  seen  project- 
ing from  the  other  block.  There  is  another  hole  through 
the  center  of  the  lower  block  threaded  for  %"  pipe — The 
step  lubricant  (oil  or  water)  is  forced  up  through  this  hole, 
and  out  between  the  raised  edges  in  a  film,  thus  floating  the 
rotating  elements  of  the  turbine  on  a  frictionless  disk  of 
lubricant.  The  upper  side  of  the  top  step  block  is  counter- 
bored  to  fit  the  lower  end  of  the  turbine  shaft,  in  which 
there  is  also  a  slot  for  the  reception  of  a  key  that  is  fitted 
across  the  top  end  of  the  step  block. 

The  counterbore  centers  the  block,  the  dowel-pins  guide 
the  key  into  the  slot,  and  the  key  causes  the  block  to  turn 
with  the  shaft.  These  are  all  close  fits,  and  when  it  be- 
comes necessary  to  remove  the  block  for  inspection  or  re- 
pairs, it  must  be  pulled  off  by  means  of  a  screw  introduced 
into  a  threaded  hole  in  the  under  side  of  the  lower  block. 
The  whole  is  supported  by,  and  rests  upon  a  large  screw  that 
passes  up  through  a  block  of  cast-iron  which  has  a  threaded 
bronze  bushing  that  forms  the  nut  for  the  screw.  The 
large  block  termed  the  cover  plate  is  held  to  the  base  of  the 
turbine  by  eight  ll/o  inch  cap  screws.  A  good  idea  of  the 
construction  may  be  gained  by  reference  to  Fig.  266  which 
is  a  section  of  the  lower  portions.  It  will  be  noticed  that  the 
%  in.  oil  supply  pipe  passes  up  through  the  entire  length 
of  the  large  step  supporting  screw,  and  connects  with  the 
oil  passage  through  the  lower  step  block. 

Clearance. — With  the  Curtis  turbine,  the  matter  of  clear- 
ance is  very  important.  There  must  be  no  rubbing  contact 


56 


Steam  Engineering 


between  the  revolving  and  stationary  buckets.  Neither 
must  there  be  too  much  clearance.  Provision  is  therefore 
made  for  inspection,  and  adjustment  of  the  clearance  in  the 
following  manner.  A  two  inch  hole  is  drilled  and  tapped 


OilDraln 


Steam 


FIG.  266 

into  each  stage,  sometimes  opposite  a  row  of  moving  blades 
and  sometimes  opposite  the  stationary  blades. 

Two  inch  plugs  are  screwed  into  these  holes,  to  be  re- 
moved when  an  inspection  is  to  be  made.    The  clearance  is 


The  Curtis  Turbine  57 

not  uniform  in  all  the  stages,  but  is  least  in  the  first  stage, 
and  greatest  in  the  last.  The  clearances  in  each  stage  of  a 
1500  K  W  machine  for  instance  are  as  follows :  1st  stage 
0.06  to  0.08,  2nd  stage  0.08  to  0.1,  3d  stage  0.08  to  0.1, 
4th  stage  0.08  to  0.2. 

These  clearances  are  measured  by  clearance  gages,  which 
are  tapering  slips  of  steel  about  l/2-m.  wide  accurately 
ground  and  graduated  by  markings,  the  difference  in  thick- 
ness of  the  gage  between  graduations  being  0.001-in.,  the 
graduations  being  %-in.  apart. 

When  it  is  desired  to  measure  the  clearance,  one  of  the 
2  inch  plugs  is  taken  out,  and  a  clearance  gage  which  has 
previously  been  rubbed  with  red  lead  is  inserted  between 
the  revolving  and  stationary  buckets  as  far  as  it  will  go, 
and  then  pulled  out. 

The  red  lead  marking  on  the  gage  will  show  how  far  it 
went  in,  and  the  nearest  graduation  in  thousandths  of  an 
inch  will  show  the  clearance,  after  noting  which,  the  red 
lead  is  rubbed  on  the  gage  again,  and  it  is  tried  on  the 
other  side,  and  if  there  is  any  difference  either  high  or  low 
it  is  corrected  by  placing  the  wheel  as  nearly  in  the  middle 
of  the  clearance  space  as  possible,  which  is  done  by  means 
of  the  step  supporting  screw  shown  in  Fig.  266. 

The  clearance  may  be  adjusted  while  the  machine  is  run- 
ning at  full  speed  in  the  following  manner :  turn  the  step 
supporting  screw  until  the  wheels  are  heard  or  felt  to  rub 
slightly,  then  mark  the  screw,  and  turn  it  in  the  opposite 
direction  until  the  wheels  rub  again.  After  marking  the 
screw  at  this  point,  it  should  be  turned  back  half  way  be- 
tween the  two  marks. 

This  method  of  adjusting  the  clearance  requires  great 
skill,  and  experience,  and  it  would  seem  that  the  gage 
method  is  to  be  preferred  for  safety. 


58  Steam  Engineering 

Packing. — The  shaft  of  the  Curtis  turbine  is  packed  with 
carbon  packing,  where  it  passes  through  the  top  head  of  the 
wheel  case.  This  packing  consists  of  blocks  of  carbon  made 
into  rings,  each  ring  consisting  of  three  segments  which 
break  joints.  These  rings  are  fitted  to  the  shaft  with  a 
slight  clearance,  and  soon  get  a  smooth  polish  which  is  not 
only  frictionless  but  steam  tight.  The-  rings  are  held  close 
to  the  shaft  either  by  light  springs,  or  the  pressure  of  the 
steam  in  the  case. 

The  Baffler. — This  is  a  device  for  restricting  the  flow  of 
water,  or  oil  to  the  step  and  guide  bearing.  Its  most  im- 
portant function  is  to  steady  the  flow  from  the  pump,  and 
maintain  a  constant  oil  film  as  the  pressure  varies  with  the 
load,  and  in  cases  where  several  machines  are  operating  on 
the  same  step-bearing  system,  the  baffler  fixes  the  flow  to 
each  machine.  The  amount,  and  pressure  of  oil  or  water 
required  to  float  a  turbine,  and  lubricate  the  guide  bearing 
depend  upon  each  other,  and  also  upon  the  condition  of  the 
step  bearing.  Usually  from  4!/2  to  5l/o  gallons  per  min- 
ute flowing  under  a  pressure  of  from  425  to  450  Ibs.  per  sq. 
in.  is  found  to  be  correct  for  a  1500  K  W  machine;  of 
course  larger  machines  require  a  heavier  pressure.  The  area 
of  the  step  bearing  must  be  considered  also.  The  principle 
upon  which  the  baffler  operates  is  as  follows :  into  the  barrel 
or  body  of  the  device  is  inserted  a  plug  which  is  simply  a 
square  threaded  worm,  the  length  of  which,  and  the  dis- 
tance it  enters  the  barrel  of  the  baffler  determining  the 
amount  of  flow.  The  more  turns  that  the  water  must  pass, 
the  less  will  be  the  flow. 


The  De  Laval  SteamTurbine 

The  De  Laval  steam  turbine,  the  invention  of  Carl 
De  Laval  of  Sweden,  is  noted  for  the  simplicity  of  its  con- 
struction and  the  high  speed  of  the  wheel— 10,000  to  30,000 
R.  P.  M.  The  difficulties  attending  such  high  velocities 
are,  however,  overcome  by  the  long,  flexible  shaft  and  the 
ball  and  socket  type  of  bearings,  which  allow  of  a  slight 
flexure  of  the  shaft  in  order  that  the  "wheel  may  revolve 
about  its  center  of  gravity,  rather  than  the  geometrical 
center  or  center  of  position.  All  high  speed  parts  of  the 
machine  are  made  of  forged  nickel  steel  of  great  tensile 
strength.  But  one  of  the  most  striking  features  of  this 
turbine  is  the  diverging  nozzle,  also  the  invention  of  De 
Laval. 

It  is  well  known  that  in  a  correctly  designed  nozzle  the 
adiabatic  expansion  of  the  steam  from  maximum  to  mini- 
mum pressure  will  convert  the  entire  static  energy  of  the 
steam  into  kinetic.  Theoretically  this  is  what  occurs  in 
the  De  Laval  nozzle.  The  expanding  steam  acquires  great 
velocity,  and,  the  energy  of  the  jet  of  steam  issuing  from 
the  nozzle  is  equal  to  the  amount  of  energy  that  would  be 
developed  if  an  equal  volume  of  steam  were  allowed  to 
adiabatically  expand  behind  the  piston  of  a  reciprocating 
engine,  a  condition,  however,  which  for  obvious  reasons 
has  never  yet  been  attained  in  practice  with  the  reciprocat- 
ing engine.  But  with  the  divergent  nozzle  the  conditions 
are  different. 

Referring  to  Fig.  267,  a  continuous  volume  of  steam 
at  maximum  pressure  is  entering  the  nozzle  at  E,  and,  pass- 

59 


60 


Steam  Engineering 


ing  through  it,  expands  to  minimum  pressure  at  F,  the 
temperature  of  the  nozzle  being  at  the  same  time  constant, 
and  equal  to  the  temperature  of  the  passing  steam.  The 


FIG.  267 
DE  LAVAL  NOZZLE 


principles  of  the  De  Laval  expanding  nozzle  are  in  fact 
more  or  less  prominent  in  all  steam  turbines.  The  facilities 
for  converting  heat  into  work  are  increased  by  its  use,  and 


The  De  Laval  Turbine  61 

the  losses  by  radiation  and  cooling  influences  are  greatly 
lessened. 

The  De  Laval  steam  turbine  is  termed  by  its  builders 
a  high-speed  rotary  steam  engine.  It  has  but  a  single 
wheel,  fitted  with  vanes  or  buckets  of  such  curvature  as 


FIG.  268 
THE  DE  LAVAL  TURBINE  WHEEL  AND  NOZZLES 

has  been  found  to  be  best  adapted  for  receiving  the  im- 
pulse of  the  steam  jet.  There  are  no  stationary  or  guide 
blades,  the  angular  position  of  the  nozzles  giving  direction 
to  the  jet.  Fig.  268  shows  the  form  of  wheel  and  the 
nozzles.  The  nozzles  are  placed  at  an  angle  of  20°  to  the 


62  Steam  Engineering 

-O 

plane   of  motion  of  the  buckets,  and  the  course   of  the 
steam  is  shown  by  the  illustration. 

The  heat  energy  in  the  steam  is  practically  devoted  to 
the  production  of  velocity  in  the  expanding  or  divergent 
nozzle,  and  the  velocity  thus  attained  by  the  issuing  jet 
of  steam  is  about  4,000  ft.  per  second.  To  attain  the 
maximum  of  efficiency  the  buckets  attached  to  the  peri- 
phery of  the  wheel  against  which  this  jet  impinges  should 
have  a  speed  of  about  1,900  ft.  per  second,  but,  owing  to 
the  difficulty  of  producing  a  material  for  the  wheel  strong 
enough  to  withstand  the  strains  induced  by  such  a  high 
speed,  it.  has  been  found  necessary  to  limit  the  peripheral 
speed  to  1,200  or  1,300  ft.  per  second. 

Fig.  269  shows  a  De  Laval  steam  turbine  motor  of  300 
H.  P.,  which  is  the  largest  size  built  up  to  the  present 
time,  its  use  having  been  confined  chiefly  to  light  work. 

The  turbine  illustrated  in  Fig.  269  is  shown  directly 
connected  to  a  200  K.  W.  two-phase  alternator.  The 
steam  and  exhaust  connections  are  plainly  shown,  as  also 
the  nozzle  valves  projecting  from  the  turbine  casing.  The 
speed  of  the  turbine  wheel  and  shaft  is  entirely  too  high 
for  most  practical  purposes,  and  it  is  reduced  by  a  pair  of 
very  perfectly  cut  spiral  gears,  usually  made  10  to  1. 
These  gear  wheels  are  made  of  solid  cast  steel,  or  of  cast 
iron  with  steel  rims  pressed  on.  The  teeth  in  two  rows 
are  set  at  an  angle  of  90°  to  each  other.  This  arrange- 
ment insures  smooth  running  and  at  the  same  time  checks 
any  tendency  of  the  shaft  towards  end  thrust,  thus  dis- 
pensing with  a  thrust  bearing. 

The  working  parts  of  the  machine  are  clearly  illustrated 
in  Fig.  270,  and  a  fairly  good  conception  of  the  assembling 


The  De  Laval  Turbine 


63 


FIG.  269 

of  the  various  members,  and  especially  the  reducing  gears, 
may  be  had  by  reference  to  Fig.  271,  which  shows  a  110 


Steam  Engineering 


FIG.  270 

H.  P.  turbine  and  rotary  pump  with  the  upper  half  of  the 
gear  case  and  field  frame  removed  for  purposes  of  inspec- 


The  De  Laval  Turbine 


65 


FIG.  271 

tion.    The  slender  shaft  is  seen  projecting  from  the  center 
of  the  turbine  case,  and  upon  this  shaft  are  shown  the 


66  Steam  Engineering 

small  pinions  meshing  into  the  large  spiral  gears  upon  the 
two  pump  shafts. 

Eef erring  to  Fig.  270,  A  is  the  turbine  shaft,  B  is  the 
turbine  wheel,  and  C  is  the  pinion.  As  the  turbine  wheel 
is  by  far  the  most  important  element,  it  will  be  taken  up 
first.  It  is  made  of  forged  nickel  steel,  and  it  is  claimed 
by  the  builders,  the  De  Laval  Steam  Turbine  Co.,  of  Tren- 
ton, New  Jersey,  that  it  will  withstand  more  than  double 
the  normal  speed  before  showing  any  signs  of  distress.  A 
clear  idea  of  the  construction  of  the  wheel  and  buckets 
may  be  had  by  reference  to  Fig.  268.  The  number  of 
buckets  varies  according  to  the  capacity  of  the  machine. 
There  are  about  350  buckets  on  a  300  H.  P.  wheel.  The 
buckets  are  drop  forged,  and  made  with  a  bulb  shank 
fitted  in  slots  milled  in  the  rim  of  the  wheel. 

Fig.  272  is  a  sectional  plan  of  a  30  H.  P.  turbine  con- 
nected to  a  single  dynamo,  and  Fig.  273  is  a  sectional  ele- 
vation of  the  same. 

The  steam,  after  passing  the  governor  valve  C,  Fig  273, 
enters  the  steam  chamber  D,  Fig.  272,  from  whence  it  is 
distributed  to  the  various  nozzles.  The  number  of  these 
nozzles  depends  upon  the  size  of  the  machine,  ranging 
from  one  to  fifteen.  They  are  generally  fitted  with  shut- 
off  valves  (see  Fig.  269)  by  which  one  or  more  nozzles  can 
be  cut  out  when  the  load  is  light.  This  renders  it  possible 
to  use  steam  at  boiler  pressure,  no  matter  how  small  the 
volume  required  for  the  load.  This  is  a  matter  of  great 
importance,  especially  where  the  load  varies  considerably, 
as,  for  instance,  there  are  plants  in  which  during  certain 
hours  of  the  day  a  300  H.  P.  machine  may  be  taxed  to  its 
utmost  capacity  and  during  certain  other  hours  the  load 
on  the  same  machine  may  drop  to  50  H.  P.  In  such  cases 


FIG.  272 


68  Steam  Engineering 

the  number  of  nozzles  in  action  may  be  reduced  by  closing 
the  shut-off  valves  until  the  required  volume  of  steam  is 
admitted  to  the  wheel.  This  adds  to  the  economy  of  the 
machine.  After  passing  through  the  nozzles,  the  steam, 
as  elsewhere  explained,  is  now  completely  expanded,  and 
in  impinging  on  the  buckets  its  kinetic  energy  is  trans- 
ferred to  the  turbine  wheel.  Leaving  the  buckets,  the 
steam  now  passes  into  the  exhaust  chamber  G,  Fig.  272, 
and  out  through  the  exhaust  opening  H,  Fig.  273,  to  the 
condenser  or  atmosphere  as  the  case  may  be. 

The  gear  is  mounted  and  enclosed  in  the  gear  case  I, 
Fig.  272.  J  is  the  pinion  made  solid  with  the  flexible 
shaft  and  engaging  the  gear  wheel  K.  This  latter  is 
forced  upon  the  shaft  L,  which,  with  couplings  M,  connects 
to  the  dynamo,  or  is  extended  for  other  transmission. 

0,  Fig.  273,  is  the  governor  held  with  a  taper  shank  in 
the  end  of  the  shaft  L,  and  by  means  of  the  bell  crank  P 
operates  the  governor  valve  C.  The  flexible  shaft  is  sup- 
ported in  three  bearings,  Fig.  272.  Q  and  R  are  the  pin- 
ion bearings  and  S  is  the  main  shaft  bearing  which  carries 
the  greater  part  of  the  weight  of  the  wheel.  This  bearing 
is  self-aligning,  being  held  to  its  seat  by  the  spring  and  cap 
shown. 

T,  Fig.  272,  is  the  flexible  bearing,  being  entirely  free  to 
oscillate  with  the  shaft.  Its  only  purpose  is  to  prevent 
the  escape  of  steam  when  running  non-condensing,  or  the 
admission  of  air  to  the  wheel  case  when  running  condens- 
ing. The  flexible  shaft  is  made  very  slender,  as  will  be 
observed  by  comparing  its  size  with  that  of  the  rotary  pump 
shaft  in  Fig.  271.  It  is  by  means  of  this  slender,  flexible 
shaft  that  the  dangerous  feature  of  the  enormously  high 
speed  of  this  turbine  is  eliminated. 


The  De  Laval  Turbine 


69 


FIG.  273 


70  Steam  Engineering 

The  governor  is  of  the  centrifugal  type,  although  dif- 
fering greatly  in  detail  from  the  ordinary  fly  ball  governor, 
as  will  be  seen  by  reference  to  Fig.  274.  It  is  connected 
directly  to  the  end  of  the  gear  wheel  shaft.  Two  weights 
B  are  pivoted  on  knife  edges  A  with  hardened  pins  C, 
bearing  on  the  spring  seat  D.  E  is  the  governor  body 
fitted  in  the  end  of  the  gear  wheel  shaft  K  and  has  seats 


FIG.  274 

milled  for  the  knife  edges  A.  It  is  afterwards  reduced  in 
diameter  to  pass  inside  of  the  weights  and  its  outer  end  is 
threaded  to  receive  the  adjusting  nut  I,  by  means  of  which 
the  tension  of  the  spring,  and  through  this  the  speed  of  the 
turbine,  is  adjusted.  When  the  speed  accelerates,  the 
weights,  affected  by  centrifugal  force,  tend  to  spread  apart, 
and  pressing  on  the  spring  seat  at  D  push  the  governor 


The  De  Laval  Turbine  71 

pin  G  to  the  right,  thus  actuating  the  bell  crank  L  and  cut- 
ting off  a  part  of  the  flow  of  steam. 

It  has  been  found  necessary  with  this  turbine,  when 
running  condensing,  to  introduce  a  valve  termed  a  vacuum 
valve,  also  controlled  by  the  governor,  as  it  has  been  found 
that  the  governor  valve  alone  is  unable  to  hold  the  speed 
of  the  machine  within  the  desired  limit.  The  function  of 
the  vacuum  valve  is  as  follows:  The  governor  pin  G  act- 
uates the  plunger  H,  which  is  screwed  into  the  bell  crank 
L,  but  without  moving  the  plunger  relative  to  said  crank. 
This  is  on  account  of  the  spring  M  being  stiffer  than  the 
spring  N,  whose  function  is  to  keep  the  governor  valve  open 
and  the  plunger  H  in  contact  with  the  governor  pin.  When 
a  large  portion  of  the  load  is  suddenly  thrown  off,  the 
governor  opens,  pushing  the  bell  crank  in  the  direction  of 
the  vacuum  valve  T.  This  closes  the  governor  valve,  which 
is  entirely  shut  off  when  the  bell  crank  is  pushed  so  far  that 
the  screw  0  barely  touches  the  vacuum  valve  stem  J. 
Should  this  not  check  the  speed  sufficiently,  the  plunger 
H  is  pushed  forward  in  the  now  stationary  bell  crank,  and 
the  vacuum  valve  is  opened,  thus  allowing  the  air  to  rush 
into  the  space  P  in  which  the  turbine  wheel  revolves,  and 
the  speed  is  immediately  checked. 

The  main  shaft  and  dynamo  bearings  are  ring  oiling. 
The  high-speed  bearings  on  the  turbine  shaft  are  fed  by 
gravity  from  an  oil  reservoir,  and  the  drip  oil  is  collected 
in  the  base  and  may  be  filtered  and  used  over  again. 

The  fact  that  the  steam  is  used  in  but  a  single  stage  or 
set  of  buckets  and  then  allowed  to  pass  into  the  exhaust 
chamber  might  appear  at  first  thought  to  be  a  great  loss 
of  kinetic  energy,  but,  as  has  been  previously  stated,  the 
static  energy  in  the  steam  as  it  enters  the  nozzles  is  con- 


Steam  Engineering 


verted  into  kinetic  energy  by  its  passage  through  the  diver- 
gent nozzles,  and  the  result  is  a  greatly  increased  volume  of 
steam  leaving  the  nozzles  at  a  tremendous  velocity,  but  at 
a  greatly  reduced  pressure — practically  exhaust  pressure — 
impinging  against  the  buckets  of  the  turbine  wheel  and 
thus  causing  it  to  revolve. 


\ 


L23 


FIG.  275 


Efficiency  tests  of  the  De  Laval  turbine  show  a  high  econ- 
omy in  steam  consumption,,  as  for  instance,  a  test  made  by 
Messrs.  Dean  and  Main  of  Boston,  Mass.,  on  a  300  H.  P. 
turbine,  using  saturated  steam  at  about  200  Ibs.  pressure 
per  sq.  in.  and  developing  333  Brake  H.  P.,  showed  a  steam 
consumption  of  15.17  Ibs.  per  B.  H.  P.,  and  the  same  ma- 
chine, when  supplied  with  superheated  steam  and  carrying 


The  De  Laval  Turbine  73 

a  load  of  352  B.  H.  P.,  r-onsumed  but  13.94  Ibs.  per  B. 
H.  P.  These  results  compare  most  favorably  with  those  of 
the  highest  type  of  reciprocating  engines. 

Fig.  275  shows  a  cross  section  of  a  300  H.  P.  De  Laval 
wheel,  showing  the  design  necessary  for  withstanding  the 
high  centrifugal  stress  to  which  these  wheels  are  subjected. 
All  De  Laval  wheels  are  tested  to  withstand  the  centrifugal 
stress  of  twice  their  normal  velocity  without  showing  signs 
of  fatigue. 

A  characteristic  feature  of  the  De  Laval  steam  turbine  is 
that  none  of  its  running  parts  are  subject  to  the  full  press- 
ure of  the  steam,  as  the  steam  is  fully  expanded  in  the  nozzle 
before  it  reaches  the  turbine  wheel.  This  feature,  which 
will  not  be  found  in  any  other  heat  motor,  is  of  great  value 
and  promising  future  in  the  direction  of  using  high  press- 
ures with  resultant  increase  in  economy  of  fuel.  The  restric- 
tion as  to  the  steam  pressure  that  can  be  used  is  found  only 
with  the  boiler,  and  as  far  as  the  steam  turbine  itself  is  con- 
cerned, it  has  been  operated  successfully  with  a  pressure  as 
high  as  3,000  Ibs.  per  square  inch. 


Allis-Chalmers  Steam  Turbine 

Fig.  276  shows  a  general  view  of  the  Allis-Chalmers 
steam  turbine,  and  although  it  is  essentially  of  the  "Par- 
sons" type,  still  there  are  a  number  of  modifications  in 
details  of  construction,  as  compared  with  the  Westinghouse- 
Parsons  steam  turbine,  some  of  which,  no  doubt  may  be 
considered  as  adding  to  the  efficiency,  and  durability  of 
the  machine. 

Fig.  277  is  a  sectional  view  of  the  "elementary"  Parsons 
type  of  steam  turbine,  and  its  various  parts  are  described 
as  follows: 

Main  bearings,  A  and  B.  Thrust  bearing,  R.  Steam 
pipe  C.  Main  throttle  valve,  D,  which  is  balanced,  and 
operated  by  the  governor.  Steam  enters  the  cylinder 
through  passage  E,  passes  to  the  left  through  the  alternate 
rows  of  stationary  and  revolving  blades,  leaving  the  cylinder 
at  F  and  passes  into  the  condenser,  or  atmosphere  through 
passage  G.  H,  J  and  K  are  the  three  steps  or  stages  of  the 
machine.  L,  M  and  N  are  the  three  balance  pistons.  0,  P 
and  Q  are  the  equalizing  passages,  connecting  the  balance 
pistons  with  the  corresponding  stages. 

Fig.  278  shows  a  sectional  veiw  of  the  "Parsons"  turbine 
with  the  Allis-Chalmers  modifications.  L  and  M  are  the 
two  balance  pistons  at  the  high  pressure  end.  Z  is  a  smaller 
balance  piston  placed  in  the  low  pressure  end,  yet  having 
the  same  effective  area  as  did  the  larger  piston  N  shown  in 
Fig.  277.  0  and  Q  are  the  two  equalizing  passages  for 
pistons  L  and  M.  Passage  P  is  omitted  in  this  construc- 
tion, and  balance  piston  Z  is  equalized  with  the  third  stage 

75 


FIG.  27(5 
THE  ALLIS-CHALMERS  STEAM  TURBINE 


The  AUis-Chatmers  Turbine 


77 


pressure  at  Y.  Valve  V  is  a  by-pass  valve  to  allow  of  live 
steam  being  admitted  to  the  second  stage  of  the  cylinder 
in  case  of  a  sudden  overload.  This  by-pass  valve  is  the 
equivalent  of  the  by-pass  valve  used  to  admit  live  steam  to 


FIG.I 

ELEMENTARY  PARSONS  TYPE   STEAM  TURBINE 

FIG.  277 


the  low  pressure  cylinder  of  a  compound  reciprocating  en- 
gine. Valve  V  is  arranged  to  be  operated,  either  by  the 
governor  or  by  hand,  as  the  conditions  may  require.  Fric- 


FIG.  278 


tionless  glands  made  tight  by  water  packing  are  provided 
at  S  and  T  where  the  shaft  passes  out  of  the  cylinder.  The 
shaft  is  extended  at  IT  and  connected  to  the  generator  shaft 
by  a  flexible  coupling. 


78  Steam  Engineering 

The  action  of  the  steam,  and  the  general  arrangement  of 
the  stationary,  and  moving  blades  is  practically  the  same 
in  the  two  turbines,  with  the  exception  that,  in  the  larger 
sizes  of  the  Allis- Chalmers  turbine  the  "balance"  pistons  for 

t 

w^WX^S^VT^ 

MOVING 
BLADES 


STATTONARY 
BLADES 


MOVING 
BLADES 


STATIONARY 

BLADES 


MOVING 
BLADES 


STATIONARY 
BLADES 


FIG.  279 

Showing  Arrangement  of  Blading  and  Course  of  the  Steam  in 
Parsons  Steam  Turbine 

neutralizing  the  end  thrust,  are  arranged  in  a  different 
manner,  the  largest  one  of  the  three  pistons  (piston  N — 
Fig.  277)  is  replaced  by  a  smaller  balance  piston. 

This  piston  presents  the  same  effective  area  for  the  steam 
to  act  upon,  as  did  the  larger  piston,  for  the  reason  that  the 


The  Allis-Chalmers  Turbine  79 

working  area  of  the  latter  in  its  original  location  consisted 
only  of  the  annular  area  included  between  its  periphery 
and  the  periphery  of  the  next  smaller  piston.  The 
pressure  of  the  steam  is  brought  to  bear  upon  this 
equalizing  piston  in  its  new  position,  by  means  of  passages 
or  ports  through  the  body  of  the  rotor,  connecting  the  third 
stage  of  the  cylinder  with  the  supplementary  cylinder,  in 
which  the  piston  revolves.  Fig.  279  shows  the  arrangement 
of  blading,  the  course  of  the  steam  being  indicated  by  the 
arrows.  The  clearances  between  the  edges  of  the  revolving 
and  stationary  blades,  as  shown  in  the  cut  are  relatively 
out  of  proportion  to  the  actual  clearances  allowed. 

This  clearance  is  preserved  by  means  of  a  small  thrust- 
bearing  provided  inside  the  housing  of  the  main  bearing. 

This  thrust-bearing  can  be  adjusted  to  locate  and  hold 
the  rotor  in  such  a  position  as  will  allow  sufficient  clear- 
ance to  prevent  actual  contact  between  the  moving  and 
stationary  blades,  and  yet  reduce  the  leakage  of  s.team  to 
a  minimum. 

The  method  by  which  the  blades  are  fitted  to  and  held 
in  the  rotor  and  cylinder  of  the  Allis-Chalmers  steam  tur- 
bine is  as  follows :  Each  blade  is  individually  formed  by 
special  machine  tools,  so  that  its  root  or  foot  is  of  an  an- 
gular, or  dove-tail  shape,  and  at  its  tip  there  is  a  projection. 
In  order  that  the  roots  of  the  blade  may  be  firml)7  held  in 
position,  a  foundation  ring,  A,  Fig.  280,  is  provided,  which 
after  being  formed  to  a  circle  of  the  proper  diameter,  has 
slots  cut  in  it  by  a  special  milling  machine. 

These  slots  are  formed  of  dove-tail  shape  to  receive  the 
roots  of  the  blades,  and  are  at  the  same  time  accurately 
spaced,  and  inclined  so  as  to  give  the  required  pitch  and 
angles  to  the  blades. 


80 


Steam  Engineering 


The  foundation  rings  are  also  of  dove- tail  shape  in  cross- 
section,  those  holding  the  stationary  blades  are  inserted 
in  dove-tail  grooves  in  the  cylinder  and  those  holding  the 
revolving  blades  being  pressed  into  the  rotor  or  spindle. 

The  rings  are  firmly  held  in  their  places  by  key-pieces 
driven  into  place  and  upset  into  under-cut  grooves,  thus 
positively  locking  the  whole  structure  together,  and  making 


FIG.  280 

it  practically  impossible  for  a  blade  to  get  out  of  place. 

The  tips  of  the  blades  are  held  and  firmly  bound  together 
by  a  shroud-ring,  B,  Fig.  280. 

The  shroud-rings  are  made  channel-shape,  in  cross-sec- 
tion, the  flanges  being  made  thin  in  order  to  prevent 
dangerous  heating  in  case  of  accidental  contact  with  either 
the  walls  of  the  cylinder  or  the  surface  of  the  rotor. 


The  Allis-Chalmers  Turbine  81 

The  bearings  of  this  turbine  are  of  the  self-adjusting 
ball  and  socket  type,  designed  for  high  speed.  Shims  are 
provided  for  proper  alignment.  The  lubrication  of  the 
four  bearings,  two  for  the  turbine,  and  two  for  the  gen- 
erator, is  accomplished  by  supplying  an  abundance  of  oil 
to  the  middle  of  each  bearing  and  allowing  it  to  flow  out 
at  the  ends  where  it  is  caught,  passed  through  a  cooler, 
and  pumped  back  to  the  bearings. 

The  fact  that  the  oil  is  supplied  in  large  quantities  to 
the  bearings  does  not  involve  a  heavy  oil  bill. 

The  journals  are  practically  floating  on  films  of  oil,  thus 
preventing  that  "wearing  out"  of  the  oil  that  occurs  when 
it  is  supplied  in  small  "doses." 

The  governor  is  driven  from  the  turbine  shaft  by  means 
of  cut  gears  working  in  an  oil-bath. 

The  governor  operates  a  balance  throttle  valve  by  means 
of  a  relay,  except  in  very  small  sizes  in  which  the  valve 
is  worked  direct. 

In  order  to  provide  for  any  possible  accidental  derange- 
ment of  the  main  governing  mechanism,  an  entirely  sep- 
arate safety,  or  over-speed  governor  is  furnished.  This 
governor  is  driven  directly  by  the  turbine  shaft  without 
the  intervention  of  gearing,  and  is  so  arranged  and  adjusted 
that  if  the  turbine  should  reach  a  predetermined  speed  above 
that  for  which  the  main  governor  is  set,  the  safety  governor 
will  come  into  action  and  trip  a  valve,  shutting  off  the 
steam  and  stopping  the  turbine.  A  strainer  is  provided 
through  which  the  steam  is  passed  before  admission  to 
the  turbine. 

For  connecting  the  rotors  of  the  turbine  and  generator 
a  special  type  of  flexible  coupling  is  used  to  provide  for  any 
slight  inequality  in  the  wear  of  the  bearings,  to  permit 


82  Steam  Engineering 

axial  adjustment  of  the  turbine  spindle,  and  to  allow  for 
differences  in  expansion.  This  coupling  is  so  made  that  it 
can  be  readily  disconnected  for  the  removal  of  the  turbine 
spindle,  or  of  the  revolving  field  of  the  generator.  Provi- 
sion is  made  for  ample  lubrication  of  the  adjoining  faces 
of  the  coupling.  The  coupling  is  enclosed  in  the  bearing 
housing,  so  that  it  is  completely  protected  against  damage, 
and  cannot  cause  injury  to  the  attendants. 

Waste  of  heat  by  radiation  is  prevented  in  the  following 
manner : 

The  hot  parts  of  the  turbine,  up  to  the  exhaust  chamber 
are  covered  with  an  ample  thickness  of  non-conducting 
material  and  lagged  with  planished  steel. 

For  large  Allis-Chalmers  turbines  the  bedplate  is  di- 
vided into  two  parts,  one  carrying  the  low-pressure  end 
of  the  turbine  and  the  bearings  of  the  generator,  the  other 
carrying  the  high-pressure  end  of  the  turbine.  The  tur- 
bine is  secured  to  the  former,  while  the  latter  is  provided 
with  guides  which  permit  the  machine  to  slide  back  and 
forth  with  differences  of  expansion  caused  by  varying  tem- 
perature, at  the  same  time  maintaining  the  alignment. 

Fig.  281  shows  the  spindle,  or  rotor  of  the  Allis-Chalmers 
turbine.  The  rings  which  carry  the  blades  are  pressed  on 
the  shaft.  Fig.  282  illustrates  the  blades  as  they  appear 
when  fitted  on  to  the  rotor.  The  shroud  ring  protecting 
the  tips  of  the  blades  is  also  shown  in  place.  Fig.  283 
shows  another  view  of  the  blade  construction.  This  is  a 
half-ring  of  blades  inserted  in  the  foundation  ring  before 
being  placed  upon  the  rotor. 

Fig.  284  shows  several  rows  of  stationary  blades  as  they 
appear,  fitted  in  the  cylinder  of  an  Allis-Chalmers  steam 
turbine. 


The  AUis-Chalmers  Turbine 


FIG.  281 
ROTOR  OF  ALLIS-CH  A LMERS  STEAM  TURBINE 


84 


Steam  Engineering 


FIG.  282 

Starting  Up.— As  a  rule  in  preparing  to  start  a  steam 
[turbine,   especially  one  of  the  "Parsons,"  type,  the   first 


The  Allis-Chalmers  Turbine  85 

move  is  to  open  the  throttle  slightly,  to  allow  as  much  steam 
as  possible  to  flow  through  the  turbine  without  causing  il 
to  start.  This  requires  but  a  few  seconds,  and  about  an 
equal  period  of  time  is  required  to  start  the  auxiliary  oil 
pump.  The  inlet  valve  is  always  left  open  to  the  surface 
condensers,  so  they  are  always  full  of  water.  The  outlet  valve 
is  quickly  opened  a  certain  number  of  turns,  which  is  known 
to  be  sufficient  for  all  purposes,  and  this  is  easily  done  be- 
fore the  moderate  amount  of  steam  flowing  through  has  had 
time  to  heat  the  condenser  unduly.  By  this  time  the  oil 
is  sufficiently  high  in  the  reservoir  to  permit  the  turbine  to 
be  started  very  slowly,  and  it  doubtless  warms  up  rather 
more  evenly  when  turning  over  than  when  standing.  When 
the  oil  has  reached  its  normal  level  in  the  reservoir,  the 
turbine  is  given  more  steam,  and  the  field  cut  in. 

The  principal  precautions  to  be  observed  are,  not  to  start 
without  properly  warming  up,  also  to  be  certain  that  the  oil 
is  circulating  freely  through  the  bearings. 

The  vacuum  should  not  be  on  until  the  water  glands  seal, 
and  care  should  be  taken  not  to  run  on  vacuum  without  a 
load  on  the  turbine. 

If  a  turbine  vibrates  objectionably  when  started  after  a 
moderate  time  has  been  allowed  for  warming,  say  6  minutes 
for  a  500-kilowatt,  10  minutes  for  a  2000-kilowatt,  and  15 
or,perhaps  20  minutes  for  larger  sizes,  it  is  highly  probable 
that  there  is  something  structurally  wrong  with  it,  and  any 
longer  period  will  do  but  little,  if  any,  good ;  furthermore, 
it  will  be  subject  to  mysterious  "spells"  or  "fits"  of  vibra- 
tion upon  changes  of  load  or  vacuum. 

In  Operation. — The  throttle,  and  inlet  gages  should  be 
closely  watched,  to  see  that  neither  the  pressure,  nor  the 
steam  temperature  varies  much.  The  vacuum  should  also 


Steam  Engineering 


FIG.  283 


The  Allis-Chalmers  Turbine 


87 


be  kept  constant,  as  well  as  the  water  glands,  and  those 
pressures  indicated  by  the  oil  gages.  The  temperature  of 
the  oil  flowing  to  and  from  the  bearings  should  not  exceed 
135°  Fahr.— . 


FIG.  284 

Shows  a  Number  of  Rows  of  Stationary  Blades  Fitted  in  the 
Cylinder  of  an  Allis-Chalmers  Steam  Turbine 

The  governor  parts  also  should  be  oiled  at  regluar 
intervals. 

Stopping  the  turbine  is  practically  the  reverse  of  start- 
ing, the  successive  steps  being  as  follows :  starting  the  aux- 


88  Steam  Engineering 

iliary  oil  pump,  freeing  it  of  water  and  allowing  it  to  run 
slowly ;  removing  the  load  gradually ;  breaking  the  vacuum 
when  the  load  is  almost  zero,  shutting  off  the  condenser 
injection  and  taking  care  that  the  steam  exhausts  freely 
into  the  atmosphere ;  shutting  off  the  gland  water  when  the 
load  and  vacuum  are  off;  pulling  the  automatic  stop  to 
trip  the  valve  and  shut  off  steam  and,  as  the  speed  of  the 
turbine  decreases,  speeding  up  the  auxiliary  oil  pump  to 
maintain  pressure  on  the  bearings;  then,  when  the  turbine 
has  stopped,  shutting  down  the  auxiliary  oil  pump,  turning 
off  the  cooling  water,  opening  the  steam  chest  drains  and 
slightly  oiling  the  oil  inlet  valve-stem.  During  these 
operations  the  chief  particulars  to  be  heeded  are:  not  to 
shut  off  the  steam  before  starting  the  auxiliary  oil  pump 
nor  before  the  vacuum  is  broken,  and  not  to  shut  off  the 
gland  water  with  vacuum  on  the  turbine.  The  automatic 
stop  should  also  remain  unhooked  until  the  turbine  is  about 
to  be  started  up  again. 

General  Suggestions. — Water  used  in  the  glands  of  the 
turbine  must  be  free  from  scale-forming  impurities,  and 
should  be  delivered  at  the  turbine  under  a  steady  pressure 
of  not  less  than  15  pounds.  The  pressure  in  the  glands 
will  vary  from  4  to  10  pounds.  This  water  may  be  warm. 
In  the  use  of  water  for  the  cooling  coils  and  of  oil  for  the 
lubricating  system,  nothing  more  is  required  than  ordinary 
good  sense  dictates.  An  absolutely  pure  mineral  oil  must 
be  supplied,  of  a  nonfoaming  charcter,  and  it  should  be 
kept  free  through  filtering  from  any  impurities. 

These  suggestions  apply  more  particularly  to  steam  tur- 
bines of  the  "Parsons"  type,  exhausting  into  condensers. 
For  turbines  built  to  be  run  non-condensing  the  portion 
relating  to  vacuum  does  not  of  course  apply. 


Hamilton-Holzwarth  Steam  Turbine 

In  order  to  thoroughly  understand  the  underlying  prin- 
ciples of  the  steam  turbine,  and  the  action  of  the  steam 
within  it,  one  must  get  definitely  fixed  in  his  mind  this 
fact,  viz.,  that  there  is  no  similarity  between  it  and  the 
reciprocating  engine,  and  the  action  of  the  steam  upon  the 
piston  in  driving  it  back  and  forth.  In  fact,  there  is  more 
similarity  between  the  reciprocating  engine  and  the  rotary 
engine  than  there  is  in  the  case  of  the  turbine.  In  the 
rotary  engine  the  steam  pushes  a  piston  in  the  same  manner 
as  it  does  in  the  reciprocating  engine,  with  the  exception 
that  the  piston  of  the  rotary  engine  travels  entirely  around 
the  shaft,  while  the  piston  of  the  reciprocating  engine 
travels  back  and  forth  in  a  straight  line  motion.  It  will 
be  much  easier  to  get  a  clear  idea  of  the  action  of  the  tur- 
bine if  one  will  for  the  time  being  drop  all  knowledge  he 
may  have  of  reciprocating  and  rotary  engines.  He  will 
then  be  able  to  more  readily  grasp,  and  better  understand 
the  action  of  the  steam  turbine. 

One  of  the  most  comprehensive,  and  at  the  time  most 
simple  explanations  of  the  action  of  the  steam  upon  the 
blades  of  the  turbine,  and  also  upon  the  piston  of  the 
reciprocating  engine,  in  both  of 'which  cases  rotary  motion 
is  produced,  but  in  two  different  ways,  is  given  by  Hans 
Holzwarth.  He  says :  "Take  a  large  wheel  which  is 
fastened  to  a  vertical  shaft.  Grasp  this  wheel  at  the  rim 
at  a  certain  point,  and  walk  continuously  around  the  shaft, 
always  retaining  the  hold,  like  a  horse  walking  around 
a  capstan  fastened  to  a  bar  or  pole  which  he  pulls  after  him. 

89 


90  Steam  Engineering 

Or  stand  still  in  a  certain  spot  and  take  the  wheel  hy  the 
rim  and  cause  it  to  revolve  (like  opening  and  closing  a 
valve  by  hand),  by  changing  hands  so  that  the  whole  rim 
is  constantly  revolving." 

The  first  illustration  clearly  explains  the  manner  in 
which  the  shaft  of  the  reciprocating  engine  is  caused  to 
revolve,  by  means  of  the  static  expansion  force  of  the  steam 
acting  upon  the  crank  pin,  through  the  medium  of 
the  piston,  piston  rod,  cross  head,  and  connecting 
rod.  In  the  second  illustration,  in  which  the  man 
turns  the  wheel  by  simply  standing  still  in  one  place,  and 
causing  the  wheel  to  revolve  by  grasping  the  rim  and  giv- 
ing it  a  push,  first  with  one  hand,  and  then  with  the  other, 
we  have  a  simple  explanation  of  how  the  steam  causes  the 
shaft  of  the  turbine  to  revolve,  by  a  constant  series  of 
pushes,  or  impulses  against  the  movable  blades  that  are  key 
seated  to  the  drum,  which  in  turn  is  keyed  to  the  shaft, 
the  moving  blades  representing  the  rim  of  our  wheel. 

Every  one  knows  that  in  order  to  be  able  to  turn  the 
aforesaid  wheel  the  man  must  have  a  good  floor  to  stand 
upon,  and  he  must  also  have  a  good  foothold  on  the  floor, 
because  he  exerts  the  same  amount  of  pressure  on  the 
floor,  that  he  exerts  against  the  rim  of  the  wheel.  This 
explains  why  there  must  be  stationary  blades,  as  well  as 
revolving  blades  in  a  turbine. 

The  actual  pressure  exerted  upon  any  single  blade  in  a 
turbine  is  in  reality  very  light.  Take,  for  example,  a  300 
K.  W.  Westinghouse  turbine.  There  are  altogether  in  a 
machine  of  this  size  31,073  blades,  of  which  16,095  are  mov- 
ing blades.  The  pressure  that  each  blade  exerts  in  turning 
the  shaft  is  a  little  over  one  ounce,  but  owing  to  the  large 
number  of  blades,  and  the  velocity  of  the  steam,  the  power 
is  developed. 


Hamilton-Hohwarth  Turbine 


91 


FIG.  285 
HAMILTON-HOLZWARTH  STEAM  TURBINE 

The    Hamilton-Holzwarth   steam   turbine   resembles   in 
many  respects  the  Westinghouse-Parsons  turbine,  prominent 


92  Steam  Engineering 

of  which  is  that  it  is  a  full  stroke  turbine ;  that  is,  the  steam 
flows  through  it  in  one  continuous  belt,  or  veil  in  a  screw 
line,  the  general  direction  being  parallel  with  the  shaft. 
But  unlike  the  Parsons  type,  the  steam  in  the  Hamilton- 
Holzwarth  turbine  is  made  to  do  its  work  only  by  impulse, 
and  not  by  impulse  and  reaction  combined.  The  smaller 
sizes  are  built  in  a  single  casing  or  cylinder,  but  for  units 
of  750  K.  W.  and  larger  there  are  two  parts,  viz.,  high 
and  low  pressure,  thus  resmbling  in  some  respects  a  com- 
pound reciprocating  engine. 

The  Hamilton-Holzwarth  steam  turbine  is  based  upon 
and  has  been  developed  from  the  designs  of  Prof.  Eateau, 
of  Paris,  and  is  being  manufactured  in  this  country  by 
the  Hooven-Owens-Rentschler  Co.,  of  Hamilton,  Ohio.  It 
is  horizontal,  and  placed  upon  a  rigid  bed  plate  of  the  box 
pattern.  All  steam,  oil  and  water  pipes  are  within  and 
beneath  this  bed  plate,  as  are  also  the  steam  inlet  valve  and 
the  regulating  and  by-pass  valves. 

There  are  no  balancing  pistons  in  this  machine,  the 
axial  thrust  of  the  shaft  being  taken  up  by  a  thrust  ball- 
bearing. The  interior  of  the  cylinder  is  divided  into  a 
series  of  stages  by  stationary  discs  which  are  set  in  grooves 
in  the  cylinder,  and  are  bored  in  the  center  to  allow  the 
shaft,  or  rather  the  hubs  of  the  running  wheels  that  are 
keyed  to  the  shaft,  to  revolve  in  this  bore. 

Clearance. — The  clearance  allowed  is  as  small  as  prac- 
ticable, as  it  is  in  this  clearance  between  the  revolving  hub 
and  the  circumference  of  the  bore  of  the  stationary  disc 
that  the  leakage  losses  occur.  It  should  be  noted  that  be- 
tween each  two  stationary  discs  there  is  located  a  running 
wheel,  and  that  the  clearance  between  the  running  vanes 
and  the  stationary  vanes  is  made  as  slight  as  is  consistent 


Hamilton-Holzwartli  Turbine  93 

with  safe  practice ;  otherwise  leakage  would  occur  here 
also,  and  besides  this  there  would  be  a  distortion  of  the 
steam  jet  and  entrainment  of  the  surrounding  atmosphere, 
resulting  in  a  rapid  decline  in  economy  if  the  clearance 
between  the  stationary  and  moving  elements  was  not  re- 
duced to  as  small  a  fraction  as  possible. 

As  before  stated,  the  stationary  discs  are  firmly  secured 
to  the  interior  walls  of  the  casing.  At  intervals  on  the 
outside  periphery  of  these  discs  are  located  the  stationary, 
or  guide  vanes.  These  are  made  of  drop  forged  steel.  They 
are  set  in  -a  groove  on  the  outside  edge  of  the  disc  and 
fastened  with  rivets.  Both  disc  and  vanes  are  then  ground, 
giving  the  vanes  the  profile  that  they  should  have  for  the 
most  efficient  expansion  of  the  steam.  After  this  is  done 
a  steel  ring  is  shrunk  on  the  outside  periphery  of  the  vanes 
and  the  steam  channels  in  the  disc.  These  discs  are  then 
placed  in  the  grooves  in  the  casing  at  regular  intervals, 
and  in  the  spaces  between  them  are  the  running  wheels. 

The  casing  is  divided  into  an  upper  and  lower  half.  The 
running  wheels  are  built  with  a  cast  steel  hub  having  a 
steel  disc  riveted  on  to  each  side,  thus  forming  a  circum- 
ferential ring  space  into  which  the  running  vanes  are 
riveted.  A  thin  steel  band  or  rim  is  tied  on  the  outer  edge 
of  the  vanes,  thus  forming  an  outer  wall  to  the  steam 
channels  and  confining  the  steam  within  the  vanes.  These 
vanes  are  also  milled  on  both  edges,  on  the  influx,  and 
efflux  side  of  the  wheel,  thus  forming  them  to  the  shape 
corresponding  to  the  theoretical  diagram. 

Tn  all  steam  turbines  one  of  the  main  requisites  for  a 
quiet-running  machine  is  that  the  revolving  element  or 
rotor  shall  be  perfectly  balanced.  The  rotary  body  of  the 
Hamilton-Holzwarth  turbine  consists  of  a  plurality  of  run- 


94  Steam  Engineering 

ning  wheels,  each  one  of  which  is  balanced  by  itself  before 
being  placed  upon  the  shaft.  All  the  bearings  are  lubri- 
cated in  a  thorough  manner  by  oil  forced  up  into  the  bot- 
tom bushing  or  shell  under  slight  pressure.  Flexible  coup- 
lings are  used  between  the  high  and  low-pressure  shafts, 
and  for  connecting  the  turbine  shaft  to  the  generator  shaft 
or  other  shaft  to  be  driven.  By  means  of  the  thrust  ball- 
bearing on  the  exhaust  end  of  the  turbine  the  shaft  may 
be  adjusted  in  an  axial  direction  in  such  a  manner  as  to 
accurately  preserve  the  desired  position  of  the  running 
wheels. 

Fig.  285  shows  a  general  view  of  the  Hamilton-Holz- 
warth  turbine,  and  the  action  of  the  steam  within  the  ma- 
chine may  be  described  as  follows:  After  leaving  the 
steam  separator  that  is  located  beneath  the  bed  plate,  the 
steam  passes  through  the  inlet  or  throttle  valve,  the  stem 
of  which  extends  up  through  the  floor  near  the  high- 
pressure  casing  and  is  protected  by  a  floor  stand  and 
equipped  with  a  hand  wheel,  shown  in  Fig.  285.  The 
steam  now  passes  through  the  regulating  valve.  From  this 
valve  it  is  led  through  a  curved  pipe  to  the  front  head  of 
the  high  pressure  casing  or  cylinder.  In  this  head  is  a 
ring  channel  into  which  the  steam  enters,  and  from  which 
it  flows  through  the  first  set  of  stationary  vanes.  In  these 
vanes  the  first  stage  of  expansion  occurs. 

Construction  of  the  Stationary  Blade. — A  stationary 
blade  is  constructed  in  the  following  manner :  A  circular 
cast-iron  disc  a,  Fig.  286,  has  a  bore  b  corresponding  to 
the  diameter  of  the  shaft,  with  the  necessary  clearance. 
On  the  outer  circumference  of  this  disc  there  is  cut  a 
groove  c.  The  stationary  guides,  consisting  of  a  vane  of 
proper  curvature  and  the  adjoining  piece,  are  of  drop- 


Hamilton-Hohwarth  Turbine 


95 


forged  steel,  milled  on  all  sides  of  the  adjoining  piece  which 
fits  into  the  circular  groove  c.  These  vanes  are  arranged 
all  around  the  circumference  so  that  one  adjoining  piece 
touches  another  and  they  are  held  in  place  and  fastened 
securely,  by  rivets  e,  to  the  disk.  The  outer  circumference 
of  these  vanes  is  turned  off  to  the  right  size,  and  then  a. 
steel  ring  f  is  shrunk  over  them.  This  shrunk  ring  pro- 
jects into  the  grooves  of  the  housing. 


Fio.  286 

The  Running  Wheel. — While  in  the  stationary  blade  the 
weight  is  not  of  great  importance,  in  the  running  wheel  it 
is  very  essential  to  reduce  the  weight  as  much  as  possible. 
It  will  be  readily  understood  that  the  lighter  the  running 
wheels  are,  the  less  the  bearings  will  have  to  support,  and 
therefore  the  shorter  they  may  be  constructed,  and  the 
better  they  will  work.  Furthermore,  by  keeping  down  the 
weight  of  the  running  wheel  the  shaft  diameter  is  kept 
within  small  limits.  This  determines  the  bore  of  the  sta- 
tionary blade,  and  with  that  the  circular  space  between  the 
bore  of  the  stationary  blade  and  the  shaft  can  be  kept 


96 


Steam,  Engineering 


within  small  limits;  therefore  in  the  construction  of  this 
running  wheel  every  dead  and  unnecessary  weight  is 
avoided. 

The  running  wheel  is  made  up  as  follows :  A  steel  hub 
or  spider  a,  Fig.  287,  has  a  bore  b  fitting  closely  to  the 
shaft  diameter.  On  both  side  of  the  hub  are  riveted  steel 
discs  c.  The  groove  on  the  outer  circumference  of  the 
steel  disc  is  turned  out  and  forms  a  receptacle  for  the 
running  vanes.  The  running  vane  itself  consists  of  the 


FIG.  287 

properly  curved  blade,  with  an  adjoining  piece  made  in  one 
section  of  drop-forged  steel.  The  adjoining  piece  is  fin- 
ished and  fits  closely  into  the  grooves  of  the  steel  disc.  The 
running  vanes  are  held  in  place  and  rigidly  connected  to 
the  steel  discs  by  rivets  d,  so  that  the  centrifugal  force  of 
each  vane  is  taken  up  by  a  rivet  and  transmitted  through 
the  rivet  to  the  steel  disc.  The  outer  edge  f  of  the  vane  is 
turned  off  and  thus  provided  with  an  annular  groove  form- 
ing a  receptacle  for  the  steel  band  .g,  which  is  tied  all 
around  the  wheel.  It  is  held  in  place  and  secured  to  the 


Hamilton-Hohwarth  Turbine  97 

vanes  by  riveting  over  the  projecting  ends  of  the  vanes. 
The  ends  of  the  band  are  brazed  together. 

Beference  to  Fig.  288,  which  is  a  vertical  section  of  this 
turbine,  will  serve  to  make  more  clear  the  action  of  the 
steam  within  the  machine.  The  turbine  casing  a,  is  made 
of  cast  iron  of  cylindrical  shape,  and  split  in  the  horizontal 
axis,  into  the  upper  half,  a,  and  the  lower  half,  b.  In  the 
horizontal  points  the  two  halves  are  bolted  together  steam 
tight.  The  lower  half,  b,  is  cast  together  with  the  pedestal, 
c,  which  is  the  support  for  the  low  pressure  bearing,  d,  and 
the  groove,  e,  for  the  stuffing  box,  f.  The  outlet  opening, 
g,  is  arranged  in  the  lower  half,  b.  This  lower  half  is  sup- 
ported on  pads  of  the  bed  plate,  h,  with  two  feet  extending 
on  the  sides,  and  fastened  thereto.  The  front  head,  i,  is 
bolted  steam  tight  to  the  flange,  k,  on  the  front  side  of 
the  casing.  In  front  of  the  head,  i,  is  located  the  regu- 
lating mechanism  pedestal,  1,  which  combines  the  high 
pressure  bearing  with  the  housing  for  regulating  mechan- 
ism, n,  and  housing,  o,  for  the  governor,  p.  A  live  steam 
pipe,  g',  is  connected  to  an  inlet  valve,  r,  and  this  to  a  main 
regulating  valve,  s,  to  the  inlet  flange  of  the  front  head,  i. 
The  passage  of  the  steam  into  this  front  or  high  pressure 
head  has  already  been  referred  to.  In  the  grooves  cut  in 
the  housing  are  the  stationary  blades,  t,  and  in  the  space 
between  the  two  following  stationary  blades  is  the  running 
wheel,  u.  All  running  wheels  fit  on  the  shaft,  v,  and  are 
keyed  to  the  shaft.  The  shaft,  v,  is  supported  in  the  high 
pressure  bearing,  m,  on  one  end,  and  in  the  low  pressure 
bearing,  d,  on  the  other  end.  The  low  pressure  bearing 
has  an  arrangement  which  allows  the  adjustment  of  the 
shaft,  v,  lengthwise  in  the  direction  of  the  turbine.  On 
the  outer  end  of  the  shaft  is  the  coupling,  w,  keyed  to  the 


98 


Steam  Engineering 


FIG.  288 

HAMILTON-HOLZWARTH  STEAM  TURBINE 
Sectional  Elevation 


Ham iHoft-Holzwarth  Turbine 


99 


shaft.  This  coupling  allows  connection  to  be  made  to 
the  generator,  pump,  or  blower,  which  is  to  be  driven  by 
the  turbine. 

The  flow  of.  the  steam  from  the  inlet  valve,  r,  to  the 
exhaust  outlet,  g,  and  the  manner  of  the  working  of  the 
steam  in  the  turbine  is  as  follows:  The  steam  passing 
through  the  main  regulating  valve,  s,  enters  the  circular 
channel  of  the  front  head,  i,  and  from  here  it  flows  through 
a  circular  slot  to  the  first  stationary  blade,  t.  Opposite  this 
circular  slot  is  arranged  a  multitude  of  vanes,  x,  Fig.  289, 


1 

3 
Jj 

J 

* 
•» 

M 

•* 

M 
& 

I 

•» 
•^ 

•«« 
•* 

\ 

pq 
M 

^ 

I 

** 
A 
•s, 

• 

M 
• 
• 
fl 

m 

I 

J 
/ 

ft*, 

•* 

3 

FIG.  2S9 

which  give  the  steam  the  right  expansion  in  the  right 
direction.  With  this  velocity  attained  in  the  stationary 
blades,  the  steam  impinges  upon  the  vanes,  u,  of  the  first 
running  wheel,  and  the  bore  of  the  housing  can  be  kept 
within  larger  limits,  because  the  steam  flowing  through 
the  vanes  is  prevented  from  flowing  rapidly  outward  by 
means  of  a  band  secured  around  the  outer  circumference 
of  the  running  wheel. 

The  running  vanes  conform  in  section  somewhat  to  the 
Parsons  type,  but  the  action  of  the  steam  upon  them,  and 


100  Steam  Engineering 

also  within  the  stationary  vanes  is  different.  The  expan- 
sion of  the  steam,  and  consequent  development  of  velocity 
takes  place  entirely  within  the  stationary  vanes,  which  also 
change  the  direction  of  flow  of  the  steam,  and  distribute 
it  in  the  proper  manner  to  the  vanes  of  the  running  wheels, 
which,  according  to  the  claims  of  the  makers,  the  steam 
enters  and  leaves  at  the  same  pressure,  thus  allowing  the 
wheel  to  revolve  in  a  uniform  pressure. 

In  the  low-pressure  casing,  which  is  larger  in  diameter 
than  the  high-pressure,  the  steam  is  distributed  in  the 
same  manner  as  it  is  in  the  high-pressure  casing.  There 
is,  however,  in  the  front  head  of  the  low-pressure  casing 
an  additional  nozzle  through  which  live  steam  may  be  ad- 
mitted in  case  of  overload.  The  design  of  this  nozzle  is 
such  that  the  live  steam  entering  and  passing  through  it, 
and  controlled  by  the  governor  exerts  no  back  pressure  on 
the  steam  coming  from  the  receiver,  but,  on  the  contrary, 
its  action  is  similar  to  the  action  of  an  injector,  that  is,  it 
tends  to  suck  the  low-pressure  steam  through  the  first  set 
of  stationary  vanes  of  the  low-pressure  turbin'e. 

The  first  stationary  disc  of  the  low-pressure  turbine  has 
guide  vanes  all  around  its  circumference,  so  that  the  steam 
enters  the  turbine  in  a  full  cylindrical  belt,  interrupted  only 
by  the  guide  vanes.  To  provide  for  the  increasing  volume 
as  the  steam  expands  in  its  course  through  the  turbine,  the 
areas  of  the  passages  through  the  distributers  and  running 
vanes  must  be  progressively  enlarged.  The  gradual  in- 
crease in  the  dimensions  of  the  stationary  vanes  permits 
the  steam  to  expand  within  them,  thus  tending  to  maintain 
its  velocity,  while  at  the  same  time  the  vanes  guide  the 
steam  under  such  a  small  angle  that  the  force  with  which 
it  impinges  the  vanes  of  the  next  running  wheel  is  as 


Hamilton-Holzwarth  Turbine  101 

effective  as  possible.  The  curvature  of  the  vanes  is  such 
that  the  steam  while  passing  through  them  will  increase  its 
velocity  in  a  ratio  corresponding  to  its  action. 

The  purpose  of  the  stationary  discs  is,  as  has  been  stated, 
to  distribute  the  steam  to  the  running  wheel.  They  also 
take  the  back  pressure  of  the  steam  as  it  impinges  the 
vanes  of  the  running  wheels,  thus  in  a  sense  acting  as 
balancing  pistons. 

The  governor  is  of  the  spring  and  weight  type,  adapted 
to  high  speed,  and  is  designed  especially  for  turbine  govern- 
ing. It  is  directly  driven  by  the  turbine  shaft,  revolving 
with  the  same  angular  velocity.  Its  action  is  as  follows: 
Two  discs  keyed  to  the  shaft  drive,  by  means  of  rollers, 
two  weights  sliding  along  a  cross  bar  placed  at  right  angles 
through  the  shaft  and  compressing  two  springs  against 
two  nuts  on  the  cross  bar.  Every  movement  of  the  weights, 
caused  by  increasing  or  decreasing  the  angular  velocity  of 
the  turbine  shaft,  is  translated  by  means  of  levers  to  a 
sleeve  which  actuates  the  regulating  mechanism.  These 
levers  are  balanced  so  that  no  back  pressure  is  exerted  upon 
the  weights.  The  whole  governor  is  closed  in  by  the  discs, 
one  on  each  side,  and  a  steel  ring  secured  by  concentric 
recesses  to  the  discs.  In  order  to  decrease  the  friction 
within  the  governor  and  regulating  mechanism,  thrust 
ball-bearings  and  frictionless  roller-bearings  are  used. 

As  previously  stated,  the  regulating  valve  is  located  be- 
neath the  bed  plate.  One  side  of  it  is  connected  by  a  curved 
pipe  with  the  front  head  of  the  high-pressure  cylinder,  and 
the  other  side  is  connected  with  the  inlet  valve.  The  regu- 
lating valve  is  of  the  double-seated  poppet  valve  type. 
Valves  and  valve  seats  are  made  of  tough  cast  steel,  to 
avoid  corrosion  as  much  as  possible,  and  the  valve  body  is 
made  of  cast  iron. 


102  Steam  Engineering 

Immediately  below  the  regulating  valve  and  forming  a 
part  of  it  in  one  steam  chamber  is  located  the  by-pass  regu- 
lating valve.  Thus  the  use  of  a  second  stuffing  box  for 
the  stem  of  this  valve  is  avoided.  The  function  of  this 
valve  is  to  control  the  volume  of  the  live  steam  supply  that 
flows  directly  to  the  by-pass  nozzles  in  the  front  head  of 
the  low-pressure  casing.  This  valve  is  also  a  double-seated 
poppet  valve. 

The  main  regulating  valve  is  not  actuated  directly  by 
the  governor,  but  by  means  of  the  regulating  mechanism. 
The  construction  and  operation  of  this  regulating  mechan- 
ism is  as  follows:  The  stem  of  the  regulating  valve  is 
driven  by  means  of  bevel  gears  by  a  shaft  that  is  supported 
in  frictionless  roller-bearings. 

On  this  shaft  there  is  a  friction  wheel  that  the  governor 
can  slide  across  the  face  of  a  continuously  revolving  fric- 
tion disc  by  means  of  its  sleeve  and  bell  crank  lever.  This 
revolving  disc  is  keyed  to  a  solid  shaft  which  is  driven  by 
a  coupling  from  a  hollow  shaft.  This  hollow  shaft  is  driven 
by  the  turbine  shaft  through  the  medium  of  a  worm  gear. 
The  solid  shaft,  with  the  continuously  revolving  friction 
disc,  can  be  slightly  shifted  by  the  governor  sleeve  so  that 
the  two  friction  discs  come  into  contact  when  the  sleeve 
moves,  that  is,  when  the  angular  velocity  changes.  If  this 
change  is  relatively  great,  the  sleeve  will  draw  the  periodi- 
cally revolving  friction  disc  far  from  the  center  of  the 
always  revolving  one,  and  this  disc  will  quickly  drive  the 
stem  of  the  regulating  valve  and  the  flow  of  steam  will  thus 
be  regulated.  As  soon  as  the  angular  velocity  falls  below 
a  certain  percentage  of  the  normal  speed,  the  driving  fric- 
tion disc  is  drawn  back  by  the  governor,  the  regulating 
valve  remains  open  and  the  whole  regulating  mechanism 
rests  or  stops,  although  the  shaft  is  still  running. 


Hamilton-Holzwarth  Turbine  103 

Should  the  angular  velocity  of  the  shaft  reach  a  point 
2.5  per  cent  higher  than  normal,  the  governor  will  shut 
down  the  turbine.  If  an  accident  should  happen  to  the 
governor,  due  to  imperfect  material  or  breaking  or  weaken- 
ing of  the  springs,  the  result  would  be  a  shut-down  of  the 
turbine. 

In  order  to  change  the  speed  of  the  turbine  while  run- 
ning, which  might  be  necessary  in  order  to  run  the  machine 
parallel  with  another  prime  mover,  a  spring  balance  is 
provided,  attached  to  the  bell  crank  lever  of  the  regulating 
mechanism.  The  hand  wheel  of  this  spring  balance  is 
outside  of  the  pedestal  for  regulating  mechanism  and  near 
the  floor-stand  and  hand  wheel.  With  this  spring  balance 
the  speed  of  the  turbine  may  be  changed  5  per  cent  either 
way  from  normal. 

All  the  bearings  of  the  turbine  are  thoroughly  lubricated 
with  oil  forced  under  pressure  by  the  oil  pump  driven  by 
means  of  worm  gearing  by  the  turbine  itself.  After  flowing 
through  the  bearings  the  oil  is  passed  through  a  filter,  and 
from  thence  to  the  oil  tank  located  within  the  bed  plate, 
from  whence  it  is  taken  by  the  oil  pump.  All  revolving 
parts  are  enclosed,  and  the  principal  part  of  the  regulating 
mechanism  operates  in  a  bath  of  oil. 

The  Stuffing-Box. — An  effective  means  of  packing  a 
swiftly  revolving  shaft  is  a  long  sleeve  surrounding  the 
shaft  with  a  very  small  radial  clearance.  The  reason  for 
this  will  be  found  in  the  throttling  action  of  the  steam  par- 
ticles revolving  with  the  shaft.  These  steam  particles  have 
a  tendency  to  fly  outwardly  and  so  prevent  the  steam  from 
passing  axially  through  the  small  clearance  between  the 
shaft  and  the  sleeve.  The  reader  will  readily  understand 
that  it  would  not  be  practical  to  use  such  a  long  sleeve  in 


104 


Steam  Engineering 


the  construction  of  a  steam  turbine,  as  this  arrangement 
would  considerably  increase  the  length  of  the  free  shaft. 
For  the  reason  that  the  deflection  of  the  shaft  depends 
upon  the  third  power  of  the  free  length  of  the  shaft,  it  is 
absolutely  necessary  to  restrict  this  free  length  as  much  as 
possible. 


FIG.  290 

In  the  Hamilton-Holzwarth  turbine,  use  is  made  of  the 
telescopic  idea;  that  is  the  entire  length  of  the  sleeve  is 
split  into  several  parts,  and  these  single  parts  are  shifted 
together.  In  Fig.  290  the  ring  A  screwed  upon  the  shaft 
projects  axially  into  a  groove  of  the  ring  B,  and  revolves 
within  it.  The  ring  B  does  not  move  at  all,  but  is  held  in 
place,  and  pressed  tightly  against  the  turbine  casing  by 
means  of  the  ring  C  which  presses  against  the  bushing  of 


Hamilton-IIohivarth  Turbine  105 

the  bearing.  By  screwing  the  ring  C  on  the  ring  B.  both 
rings  are  forced  axially  in  opposite  directions.  From  the 
casing  S  the  steam  seeking  to  escape,  flows  axially  to  T. 
From  there  it  flows  back  to  U,  and  then  forward  to  V, 
being  very  much  throttled  in  the  process.  The  ring  B  has 
an  annular  groove  which  must  be  packed  with  soft  packing. 
Any  accumulating  water  is  collected  in  the  chamber  W,  in 
the  bushing  of  the  bearing,  from  whence  it  is  properly 
drained.  The  ring  E  serves  only  the  purpose  of  tightening 
the  threads  between  rings  C  and  B. 


The  Rateau  Steam  Turbine 

The  Bateau  turbine  is  purely  an  impulse  turbine,  using 
wheels  of  thin  plates  pressed  into  a  slightly  conical  form. 
These  are  mounted  on  a  common  shaft,  and  separated  from 
each  other  by  division  walls.  The  first  wheels  have  partial 
peripheral  admission,  so  that  the  peripheral  velocity  may  be 
high  from  the  very  beginning  without  using  too  short 
blades.  The  guide  blades  are  set  into  division  walls,  and 
the  rotating  blades  are  bent  from  a  single  piece  of  bronze, 
or  steel  plate,  and  are  riveted  to  the  double  turned  rim  of 
the  wheel-disc.  The  shaft  bearings  were  originally  built 
as  part  of  the  cover  of  the  turbine,  but  now  are  made  inde- 
pendent. At  the  low  pressure  end  the  shaft  is  made  steam 
tight  by  means  of  a  simple  stuffing  box,  into  which  suffi- 
cient water  is  allowed  to  flow  to  secure  steam  tightness. 
As  the  same  pressure  exists  on  both  sides  of  each  rotating 
wheel,  the  axial  thrust  has  only  the  small  value  due  to  the 
pressure  on  the  area  of  the  end  of  the  front  journal. 

Fig.  291  shows  a  sectional  view  of  the  machine,  in  which 
it  is  to  be  noted  that  the  wheel  discs  are  riveted  to  their 
hubs. 

Fig.  292  shows  a  view  of  the  turbine  with  generator,  and 
oil  equipment.  The  construction  of  the  wheels,  and  division 
walls  can  easily  be  seen  in  Figs.  293,  294  and  295.  The 
construction  according  to  the  latter  figure,  with  division 
walls  made  in  sections  is  preferred,  because  after  taking 
away  the  casing  cover,  all  the  interior  parts  are  easily 
accessible. 

107 


108 


Steam  Engineering 


FIG.  291 

The  most  recent  Bateau  turbine  is  of  the  action  type, 
that  is  to  say,  expansion  of  the  steam  is  fully  carried  out  in 


The  Bateau  Turbine 


109 


•u 


FIG.  292 

the  distributor  for  each  group  consisting  of  a  distributor 
and  one  moving  wheel.     The  steam  therefore  acts  by  its 


no 


Steam  En  gin  eering 


velocity  and  not  by  its  pressure.  These  turbines  are  more- 
over multicellular,  that  is  to  say.,  they  consist  of  a  certain 
number  of  elements,  each  element  comprising  one  dis- 
tributor and  one  moving  wheel. 

This  turbine  has  been  developed  by  the  firm  of  Sautter- 


FIG.  293 

Hartle,  of  Paris,  France,  from  designs  by  Prof.  A.  Rateau, 
who  is  also  the  inventor  of  the  Eateau  steam  regenerator, 
through  which  the  exhaust  from  non-condensing  recipro- 
cating engines  may  be  passed  to  a  low-pressure  turbine, 
thus  resulting  in  the  development  of  power  from  steam 
which  otherwise  would  be  wasted.  A  very  complete  and 


The  Rateau  Turbine 


111 


successful  installation  of  this  character  has  been  in  opera- 
tion for  some  time  at  the  extensive  steel  works  of  the  Inter- 
national Harvester  Company  at  Chicago,  111.,  and  judging 
from  the  results  of  an  exhaustive  series  of  tests  conducted 
by  Mr.  F.  G.  Gaesch,  and  published  in  the  June,  1907, 
issue  of.  "Power,"  the  system  possesses  considerable  merit. 
The  following  description  of  the  installation  at  the  Har- 
vester Company's  plant,  is  supplied  by  courtesy  of  the 
Western  Electric  Co.,  of  Chicago. 


FIG.  294 

The  Steam  Regenerator,  or  accumulator,  consists  of  a 
cylindrical  wrought-steel  shell  %  of  an  inch  in  thickness, 
11  feet  6  inches  in  diameter,  and  30  feet  long,  having  a 
central  horizontal  diaphragm  which  divides  the  regenerator 
into  twQ  similar  compartments.  In  each  compartment 
there  are  six  elliptical  tubes  or  steam-distributing  conduits, 
A,  Fig.  296,  which  extend  from  end  to  end  in  pairs,  and 
are  so  placed  as  to  leave  spaces,  B,  between  them.  (The 


112  Steam  Engineering 

sectional  view  is  from  another  installation  and  only  shows 
four  tubes.)  Baffle  plates,  C,  are  arranged  above  the  space 
between  each  pair  of  tubes.  The  spaces  surrounding  the 
conduits,  and,  under  certain  conditions,  even  the  conduits 
themselves,  are  filled  with  water  to  the  extent  that  the  top 
of  the  latter  is  usually  submerged  three  or  four  inches. 
The  sides  of  the  conduits  are  perforated  with  a  great  many 
%-inch  holes  to  allow  of  the  lateral  escape  of  steam  through 


FIG.  295 

the  water,  with,  occasionally,  a  further  escape  from  the 
bottom  openings.  A  large  baffle  plate  in  the  upper  steam 
space  serves  for  a  perfect  separation  of  entrained  moisture 
from  the  steam.  The  steam  enters  by  the  pipe  shown  at  the 
left  hand  of  the  side  elevation,  passes  to  the  interior  of  the 
elliptical  tubes,  and  escapes  into  the  spaces  through  the 
perforations.  The  circulation  of  the  water  takes  place  in 
the  direction  of  the  arrows;  the  baffle  plates  placed  above 
each  pair  of  tubes  prevent  the  water  from  being  thrown 


The  Rateau  Turbine  113 

into  the  steam  space.  This  flow  of  steam  gives  an  extreme 
degree  of  steam  saturation  to  the  water;  and  the  slight 
back  pressure  which  at  first  might  be  expected,  owing  to  the 
head  of  water  above  the  rows  of  perforations,  is  thereby 
reduced  to  insignificant  proportions. 

When  the  supply  of  steam  from  main  engine  ceases,  the 
water  liberates  part  of  the  heat  it  has  absorbed,  and  an  even 
flow  of  low-pressure  steam  is  given  off,  while  the  steady 
demand  of  the  turbine  reduces  the  pressure  in  the  accumu- 
lator, causing  the  steam  still  retained  in  the  tubes  to  escape, 
maintaining  the  circulation  of  the  water,  and  facilitating 
the  liberation  of  the  steam.  Experience  has  shown  that  the 
whole  of  the  contained  water  participates  in  the  regenera- 
tive action.  The  steam  is  taken  from  the  top  of  the  ac- 
cumulator to  the  turbine,  and  the  pressure  can  be  regu- 
lated by  the  relief  valve  shown.  The  water  level  is  main- 
tained constant  by  a  ball  float  contained  in  a  small  tank 
arranged  at  the  back  of  the  regenerator.  Generally  there  is 
a  slight  overflow  at  all  times,  representing  among  other 
things  the  "make  up"  from  the  exhaust  steam  supply.  The 
regenerator  at  this  plant  has  a  capacity  of  55  tons  of  water, 
sufficient  by  actual  test  to  deliver  all  the  steam  for  a  50 
per  cent  overload  on  the  turbine  for  a  period  of  430 
seconds.  At  full  load  this  would  correspond  to  a  period 
of  390  seconds.  The  regenerator  or  accumulator  is  fitted 
with  the  following  accessories:  First,  an  adjustible  relief 
valve,  which  regulates  the  limits  of  pressure  in  the  accumu- 
lator, and  allows  the  steam  to  escape  when  the  turbine  is 
stopped,  or  working  on  a  light  load;  it  also  prevents  back 
pressure  in  the  cylinders  of  the  reciprocating  engine. 

This  valve  may  be  connected  to  the  condenser  so  that  in 
case  the  turbine  is  shut  down  for  a  period,  the  main  engines 
may  have  the  benefit  of  the  vacuum. 


114 


Steam  Engineering 


FIG.  296 
PLAN  AND  ELEVATION  OF  LOW-PRESSURE  TURBINE  INSTALLATION, 

WITH   TRANSVERSE  AND  LONGITUDINAL  SECTIONS  OF 
REGENERATOR 

Second,  a  non-return  water  valve,  necessary  with  water 
accumulators,  to  prevent  any  possibility  of  reflux  of  water 
toward  the  main  engines  during  periods  of  stoppage. 


The  Rateau  Turbine  115 

Third,  automatic  level  regulators,  and  gauge  glasses,  and 
automatic  drains. 

Fourth,  piping  beginning  at  the  inlet  of  the  receiving 
drum,  including  the  steam  header  and  mains  from  the 
regenerator  to  the  turbine,  the  exhaust  piping  from  the 
turbine,  and  condenser,  and  the  piping  between  the  con- 
denser and  air  pump. 

Fifth,  a  vertical  receiving  drum  9  feet  in  diameter,  and 
22  feet  long,  with  baffle  plates,  and  separating  chambers, 
the  function  of  which  is  to  allow  the  ready  escape  of  steam 
from  the  main  engines  without  increase  of  back  pressure 
on  the  system.  The  expansions  allowed  in  this  drum  con- 
duce to  a  more  even  flow  of  steam  in  the  steam  regenerator. 

Sixth,  a  30-inch  barometric  condenser  of  the  Alberger 
type,  complete  with  air  cooler,  exhaust  entrainer,  expan- 
sion joint,  and  an  air  pump  8x6x12  inches. 

The  exhaust  steam  from  a  42x60  Mclntosh  &  Hemphill, 
rolling  mill  engine,  passes  through  the  regenerator  and  into 
a  Eateau  low-pressure  turbine,  to  the  shaft  of  which  is 
connected  two  direct  current  generators,  each  of  250  K.  W. 
capacity,  at  250  volts,  and  designed  so  that  they  may  be 
operated  in  parallel.  The  bearings  are  of  the  ring  oiled 
reservoir  type,  with  water  jackets.  The  plant  is  designed 
with  a  view  of  adding  another  similar  unit,  but  the  evidence 
of  the  tests  shows  that  a  750  K.  W.  unit  can  be  operated 
with  the  steam  that  is  available,  without  allowance  for  the 
steam  (about  6,000  Ibs.  per  hour)  that  is  available  from 
auxilliary  machinery. 

Part  of  these  auxiliaries  already  exhaust  into  an  open 
feed  water  heater,  but  the  steam  regenerator,  constituting 
a  perfect  feed  heating  device,  can  more  appropriately  re- 
ceive all  the  steam  from  the  auxiliaries,  with  the  advantage 
of  some  addition  to  the  capacity  of  the  turbine  equipment. 


11G 


Steam  Engineering 


Fig.  297  shows  a  view  of  the  regenerator  and  attached 
equipment. 

The  leading  objects  of  the  tests  made  by  Mr.  Gaesch  were, 
first  to  determine  the  steam  consumption  of  the  turbine 


ft 


FIG.  297 
BATEAU  REGENERATOR,  AND  ATTACHED  CONDENSER 

per  unit  of  power,  and  second,  to  measure  the  actual 
amount  of  steam  available  for  the  use  of  the  turbine  as 
delivered  from  the  main  engine. 


The  Bateau  Turbine  117 

Space  prohibits  a  detailed  description  of  the  method  of 
conducting  the  tests,  and  the  results  derived  therefrom. 

The  average  brake  horse  power  developed  by  the  turbine 
according  to  the  report  of  one  of  the  tests  was  544  with  a 
steam  consumption  per  B.  H.  P.  per  hour  of  37  Ibs.  The 
average  steam  pressure  at  the  turbine  was  16.6  Ibs.  absolute. 
The  average  I.  H.  P.  of  the  main  engine  during  the  same 
test  was  820.,  with  a  steam  consumption  of  61.2  Ibs.  per 
I.  H.  P.  per  hour.  The  total  weight  of  steam  available 
per  hour  from  regenerator  to  turbine  was  56,100  Ibs. 

The  main  engine,  the  dimensions  of  which  have  already 
been  given,  was  a  reversing  rolling  mill  engine.  The  stuff- 
ing box  used  in  the  Rateau  turbine  is  clearly  illustrated  in 
Figs.  240  to  243. 


The  Reidler-Stumpf  Steam  Turbine 

This  turbine  is  manufactured  in  Germany  and  its  essen- 
tial characteristics  are  the  peculiarly  formed,  parallel  re- 
turn buckets  derived  from  the  Pelton  water  wheel,  also  the 
rectangular  nozzles  that  allow  a  homogeneous  jet  of  steam 
to  be  directed  against  the  wheel.  Fig.  298  shows  a  view 


FIG.  298 

of  one  of  the  wheels,  and  Fig.  299  shows  sections  of  a 
bucket,  and  nozzle. 

The  buckets  are  worked  out  of  a  solid  forged  wheel  with 
a  milling  cutter,  consequently  they  are  very  strong,  and 
durable. 

119 


120 


Steam  Engineering 


The  steam  jet  enters  the  bucket  C  from  the  nozzle  B,  and 
is  deflected  through  an  angle  of  180  degrees,  the  direction 


FIG.  299 


of  its  exit  being  parallel  to  that  of  its  entrance,  as  shown 
by  the  arrows  (Fig.  299). 


The  Reidler- Stump  f  Steam  Turbine 


121 


This  type  of  wheel  has  but  a  one-sided  discharge — Fig. 
300  shows  another  type  of  this  turbine,  in  which  the  sta- 


FIG.  300 


tionary  buckets  D,  of  the  reverse  guide  are  opposed  to  the 
rotating  buckets  C  of  the  wheel  in  such  a  manner  as  to 
form  a  continuous  closed  cylinder  in  wjuch  the  steam  in 


122  Steam  Engineering 

its  course  through  the  wheel  continually  whirls  or  spirals 
around  and  around.  With  this  type  of  turbine  the  steam 
enters  the  bucket  wheel  from  the  nozzle  as  shown  in  Fig. 
299,  but  instead  of  escaping  after  it  has  passed  once 
through  the  bucket,  it  is  caught  by  the  guide  or  stationary 
bucket  and  returned  to  the  wheel,  this  process  being  re- 
peated again  and  again  until  practically  all  of  the  energy 
in  the  steam  has  been  abstracted. 


FIG.  301 

Fig.  301  shows  a  portion  of  the  rim  of  this  style  of 
wheel  with  its  symmetrical  double  buckets.  The  steam  jet 
is  split  into  two  symmetrical  parts  by  the  sharp  middle  par- 
tition. The  direction  of  flow  of  the  two  steam  streams 
is  now  reversed,  and  they  are  returned  to  the  middle  plane 
of  the  wheel  by  the  reverse  blades,  and  again  brought  to  the 
wheel  as  a  united  jet.  Nearly  the  entire  periphery  has 
primary,  or  secondary  admission,  and  as  a  result  of  thi? 
the  fan  work  of  the  idle  blades  is  reduced  to  a  minimum. 


Disposal  of  the  Exhaust  Steam  of 
Steam  Turbines 

As  in  the  case  of  the  reciprocating  engine,  the  highest 
efficiency  in  the  operation  of  the  steam  turbine  is  obtained 
by  allowing  the  exhaust  steam  to  pass  into  a  condenser, 
and  experience  has  demonstrated  that  it  is  possible  to  main- 
tain a  higher  vacuum  in  the  condenser  of  a  turbine  than  in 
that  of  a  reciprocating  engine.  This  is  due,  no  doubt,  to 
the  fact  that  in  the  turbine  the  steam  is  expanded  down 
to  a  much  lower  pressure  than  is  possible  with  the  recipro- 
cating engine. 

The  condensing  apparatus  used  in  connection  with  steam 
turbines  may  consist  of  any  one  of  the  modern  improved 
systems,  and  as  no  cylinder  oil  is  used  within  the  cylinder 
of  the  turbine,  the  water  of  condensation  may  be  returned 
to  the  boilers  as  feed  water.  If  the  condensing  water  is 
foul  or  contains  matter  that  would  be  injurious  to  the 
boilers,  a  surface  condenser  should  be  used.  If  the  water 
of  condensation  is  not  to  be  used  in  the  boilers,  the  jet 
system  may  be  employed.  Another  type  of  condenser  that 
is  being  successfully  used  with  steam  turbines  is  the  Bulk- 
ley  injector  condenser. 

Among  the  steam  turbines  that  were  on  exhibition  at  the 
St.  Louis  exposition  in  1904  the  Westinghouse-Parsons  and 
the  General  Electric  Curtis  turbines  were  each  equipped 
with  Worthington  surface  condensers,  fitted  with  improved 
auxiliary  apparatus  consisting  of  dry  vacuum  pumps,  either 
horizontal  of  the  well-known  Worthington  type,  or  rotative 

123 


124  Steam  Engineering 

motor-driven,  a  hot  well  pump,  and  a  pump  for  disposing 
of  the  condensed  steam  from  the  exhaust  system.  The  two 
latter  pumps  were  of  the  Worthington  centrifugal  type. 
The  Hamilton-Holzwarth  turbine  was  equipped  with  a 
Smith- Vaile  surface  condenser,  fitted  with  a  duplex  double- 
acting  air  pump,  a  compound  condensing  circulating  pump, 
and  a  rotative  dry  vacuum  pump,  motor-driven.  The 
vacuum  maintained  was  high,  28  to  28.5  in. 

As  an  instance  of  the  great  gain  in  economy  effected  by 
the  use  of  the  condenser  in  connection  with  the  steam  tur- 
bine, a  750  K.  W.  Westinghouse-Parsons  turbine,  using 
steam  of  150  Ibs.  pressure  not  superheated  and  exhausting 
into  a  vacuum  of  28  in.,  showed  a  steam  consumption  of 
13.77  Ibs.  per  B.  H.  P.  per  hour,  while  the  same  machine 
operating  non-condensing  consumed  28.26  Ibs.  of  steam  per 
B.  H.  P.  hour.  Practically  the  same  percentage  in  economy 
effected  by  condensing  the  exhaust  applies  to  the  other 
types  of  steam  turbines. 

With  reference  to  the  relative  cost  of  operating  the  sev- 
eral auxiliaries  necessary  to  a  complete  condensing  outfit, 
the  highest  authorities  on  the  subject  place  the  power  con- 
sumption of  these  auxiliaries  at  from  2  to  7  per  cent  of  the 
total  turbine  output  of  power.  A  portion  of  this  is  re- 
gained by  the  use  of  an  open  heater  for  the  feed  water, 
into  which  the  exhaust  steam  from  the  auxiliaries  may 
pass,  thus  heating  the  feed  water  and  returning  a  part  of 
the  heat  to  the  boilers. 

A  prime  requisite  to  the  maintenance  of  high  vacuum, 
with  the  resultant  economy  in  the  operation  of  the  con- 
densing apparatus,  is  that  all  entrained  air  must  be  ex- 
cluded from  the  condenser.  There  are  various  ways  in 
which  it  is  possible  for  air  to  find  its  way  into  the  con- 


Exlawd  Steam  125 

densing  system.  For  instance,  there  may  be  an  improperly 
packed  gland,  or  there  may  be  slight  leaks  in  the  piping,  or 
the  air  may  be  introduced  with  the  condensing  water.  This 
air  should  be  removed  before  it  reaches  the  condenser,  and 
it  may  be  accomplished  by  means  of  the  "dry"  air  pump. 

This  dry  air  pump  is  different  from  the  ordinary  air 
pump  that  is  used  in  connection  with  most  condensing 
systems.  The  dry  air  pump  handles  no  water,  the  cylinder 
being  lubricated  with  oil  in  the  same  manner  as  the  steam 
cylinder.  The  clearances  also  are  made  as  small  as  possi- 
ble. These  pumps  are  built  either  in  one  or  two  stages. 

A  barometric  or  a  jet  condenser  may  be  used,  or  a  surface 
condenser.  The  latter  type  lessens  the  danger  of  entrained 
air,  besides  rendering  it  possible  to  return  the  condensed 
steam,  which  is  pure  distilled  water,  to  the  boilers  along 
with  the  feed  water,  a  thing  very  much  to  be  desired  in 
localities  where  the  water  used  for  feeding  the  boilers  is 
impregnated  with  carbonate  of  lime,  or  other  scale-form- 
ing ingredients. 

In  comparing  the  efficiency  of  the  reciprocating  engine 
and  the  steam  turbine  it  is  not  to  be  inferred  that  recipro- 
cating engines  would  not  give  better  results  at  high  vacuum 
than  they  do  at  the  usual  rate  of  25  to  26  in.,  but  to  reach 
and  maintain  the  higher  vacuum  of  28  to  28.5  in.  with  the 
reciprocating  engine  would  necessitate  much  larger  sizes 
of  the  low-pressure  cylinder,  as  also  the  valves  and  exhaust 
pipes,  in  order  to  handle  the  greatly  increased  volume  of 
steam  at  the  low  pressure  demanded  by  high  vacuum. 

The  steam  turbine  expands  its  working  steam  to  within 
1  in.  of  the  vacuum  existing  in  the  condenser,  that  is,  if 
there  is  a  vacuum  of  28  in.  in  the  condenser  there  will  be 
27  in.  of  vacuum  in  the  exhaust  end  of  the  turbine  cylinder. 


!';?(>  Steam   Engineering 

On  the  other  hand,  there  is  usually  a  difference  of  4  or  5 
in  (2  to  2.5  Ibs.)  between  the  mean  back  pressure  in  the 
cylinder  of  a  reciprocating  condensing  engine,  and  the 
absolute  back  pressure  in  the  condenser. 

It  therefore  appears  that  the  gain  in  economy  per  inch 
increase  of  vacuum  above  25  in.  is  much  larger  with  the 
turbine  than  it  is  with  the  reciprocating  engine.  Mr.  J.  R. 
Bibbins  estimates  this  gain  to  be  as  follows :  between  25  and 
28  in.  there  is  a  gain  of  31/2  to  4  per  cent  per  inch  of  in- 
crease, and  at  2&  in.  5  per  cent.  These  results  have  been 
obtained  by  means  of  exhaustive  tests  conducted  by  Mr. 
Bibbins.  Other  high  authorities  on  the  steam  turbine  all 
agree  as  to  the  great  advantages  to  be  derived  by  incurring 
the  extra  expense  of  erecting  a  condensing  plant  that  is 
capable  of  maintaining  the  high  vacuum  necessary  to  high 
efficiency. 

Another  method  by  which  the  steam  consumption  of  the 
turbine  may  be  materially  decreased,  and  a  great  gain  in 
economy  effected  is  by  superheating  the  steam.  The  amount 
of  superheat  usually  specified  is  100°,  and  the  apparatus 
employed  for  producing  it  may  be  easily  mounted  in  the 
path  of  the  waste  gases.  The  steam  may  thus  be  super- 
heated without  extra  cost  in  fuel,  and  an  increase  of  8  to 
10  per  cent  in  economy  effected.  The  independent  super- 
heater requires  extra  fuel  and  labor,  and  the  gain  in  this 
case  is  doubtful,  but  there  can  be  no  question  as  to  the  wis- 
dom of  utilizing  the  waste  flue  gases  for  superheating  the 
steam. 

As  previously  stated,  the  steam  turbine  is  peculiarly 
adapted  for  the  use  of  highly  superheated  steam,  and  high 
vacuum,  and  in  these  two  particulars  it  excels  the  recipro- 
cating engine.  At  the  present  time  many  large  plants  are 


Exhaust  Steam  127 

equipped  with  turbine  engines  that  are  giving  the  best  of 
results.,  and  the  outlook  for  the  future  employment  of  this 
type  of  power  producer  is  certainly  very  promising. 

Surface  Condensers. — The  demand  for  efficient  service  in 
the  production  of  power  by  both  the  reciprocating  engine, 
and  the  steam  turbine  has  resulted  in  bringing  to  bear  upon 
the  design  of  the  surface  condenser,  some  of  the  thought, 
study  and  experiment  which  have  heretofore  been  expended 
upon  the  other  factors  of  the  power  plant.  Up  to  within 
the  past  few  years  the  surface  condenser  consisted  princi- 
pally of  an  indiscriminate  collection  of  tubes  within  a  metal 
box,  with  a  flood  of  water  following  what  happened  to  be  the 
path  of  least  resistance,  with  tubes  subjected  upon  the  steam 
side  to  a  shower  of  water  of  condensation,  keeping  the  steam 
from  contact,  and  with  pockets  and  quiet  corners  for  steam 
and  air  and  water,  with  an  air-pump  large  enough  for  what- 
ever happened,  and  little  attention  paid  to  the  getting  of 
the  air  into  it,  the  surface  condenser  has  satisfied  the  mod- 
erate demands  of  the  past,  and  awaited  the  demands  created 
by  the  turbine,  and  the  strenuous  central  station  man  for 
scientific  treatment  along  rational  lines. 

In  a  condenser  taking  care  of  200,000  pounds  of  steam 
per  hour,  over  55  pounds  of  water  are  made  upon  the  tubes 
per  second.  If  this  has  to  drip  down  over  the  bank  below 
the  point  at  which  it  is  formed,  it  can  readily  be  seen  that 
the  lower  tubes  are  going  to  be  busy  cooling  off  feed-water 
instead  of  condensing  steam,  and  that  the  greater  rate  of 
condensation  will  occur  upon  the  upper  tubes.  By  arrang- 
ing the  tubes  in  banks,  the  condensation  from  each  of  which 
is  quickly  drawn  to  the  side  and  disposed  of,  by  leading 
the  steam  to  a  positive  and  rapid  flow  among  these  tubes 
in  a  direction  counter  to  the  flow  of  the  water,  so  that  the 


128  Steam  Engineering 

final  contact  of  the  condensed  steam  and  air  is  with  ,the 
coolest  water,  and  by  subdividing  the  flow  so  that  the  circu- 
lating water  travels  positively  and  rapidly  past  every  square 
foot  of  the  cooling  surface,  the  condenser  is  made  to  con- 
dense eighten  or  twenty  instead  of  six  pounds  of  steam  per 
hour  per  square  foot  of  surface.  The  significance  of  this, 
not  only  in  first  cost  and  space  occupied,  but  in  mainte- 
nance charges  where,  as  in  some  of  the  large  stations  upon 
the  Atlantic  seaboard,  tubes  have  to  be  renewed  once  in 
about  three  years,  is  easy  to  appreciate,  and  it  is  not  the  tube 
which  is  condensing  lots  of  steam,  but  rather  that  which  is 
loafing  in  an  air  pocket  or  an  eddy,  that  is  the  most  likely 
to  corrode. 

Notwithstanding  the  liability  to  corrosion  of  the  tubes 
of  surface  condensers,  many  of  the  large  engine  plants,  and 
practically  all  steam  turbine  plants  have  been  equipped 
with  surface  condensers.  This  is  due  largely  to  the  saving 
effected  by  returning  the  pure  water  of  condensation  to 
the  boilers.  But  unless  the  condenser  tubes  are  closely 
watched  for  signs  of  corrosion,  there  is  danger  of  having 
in  the  course  of  time  a  mixture  of  cylinder  oil  and  con- 
denser leakage  along  with  the  water  of  condensation,  which 
would  be  a  very  undesirable  boiler  feed.  This  applies  to 
reciprocating  engine  plants.  On  the  other  hand  a  surface 
condenser  in  connection  with  a  steam  turbine  is  a  better 
investment.  The  turbine  water  of  condensation  contains 
no  lubricating  oil  and  condenser  leakage  is  the  only  source 
of  trouble  to  be  feared.  To  maintain  this  condenser  leak- 
age at  the  lowest  practicable  minimum  is  extremely  im- 
portant, as  this  will  seriously  affect  (if  the  hot-well  water 
is  used  for  boiler  feed)  the  percentage  of  corrosive  and 
scale-forming  elements  fed  into  the  boilers.  Even  under 


Questions  and  Answers  129 

normal  surface-condenser  operation  there  is  a  small  leakage, 
through  the  packing  at  the  ends  of  the  tubes,  and  to  this 
is  added  leakage  due  to  corrosion. 

The  danger  of  corrosion  attacking  the  tubes  of  surface 
condensers  is  much  greater  in  localities  upon,  or  near  the 
sea  coast  where  the  condensing  water  is  largely  impreg- 
nated with  salt. 

QUESTIONS   AND  ANSWERS. 

446.  Explain   the   chief   points   of   difference   between 
the  action  of  the  reciprocating  steam  engine,  and  the  steam 
turbine. 

Ans.  The  piston  of  the  reciprocating  engine  is  driven 
back  and  forth  by  the  static  expansive  force  of  the  steam ; 
while  in  the  steam  turbine,  not  only  is  this  static  expansive 
force  made  to  do  work,  but  the  velocity  of  the  steam  in  ex- 
panding from  a  high,  to  a  low  pressure  is  also  utilized  in 
turning  the  rotor  of  the  turbine. 

447.  What  other  important  factors  enter  into  the  opera- 
tion of  a  steam  turbine? 

Ans.     The  principles  of  reaction  and  impulse. 

448.  Name  several  of  the  more  important  advantages 
that  the  turbine  has  over  the  reciprocating  engine. 

Ans.  First,  highly  superheated  steam  of  a  high  initial 
pressure  may  be  used  in  the  turbine.  Second,  a  larger 
proportion  of  the  heat  in  the  steam  may  be  converted  into 
work  with  the  turbine.  Third,  there  is  much  less  friction 
with  the  turbine. 

449.  What  is  the  most  economical  method  of  disposing 
of  the  exhaust  steam  from  a  turbine? 

Ans.     By  allowing  it  to  pass  into  a  condensei. 


130  Steam  Engineering 

450.  Will  the  turbine  expand   the  steam  to  as  low   n 
pressure  as  the  reciprocating  engine  will? 

Ans.     Yes,  and  even  lower. 

451.  What  type  of  condensing  apparatus  is  necessary 
with  the  steam  turbine. 

Ans.     The  same  kind  that  is  used  on  reciprocating  en- 
gines. 

452.  How  low  will  a  well  regulated  turbine  allow  the 
steam  to  expand  ? 

Ans.  To  within  one  inch  of  the  vacuum  existing  in 
the  condenser. 

453.  What  is  the  theoretical  velocity  of  steam  under 
100  Ibs.  pressure  if  allowed  to  discharge  into  a  vacuum  of 
28  inches? 

Ans.     3860  feet  per  second. 

454.  How  many  ft.  Ibs.  of  energy  would  one  cubic  ft. 
of  steam  thus  exert? 

Ans.     59,900  ft.  Ibs. 

455.  What  is  the  ratio  of  bucket  speed  to  jet  speed  for 
impulse  wheels. 

Ans.     Bucket  speed  equals  one-half  of  jet  speed. 

456.  What  should  be  the  ratio  between  bucket  speed 
and  jet  speed,  for  reaction  wheels. 

Ans.     1  to  1.     That  is,  the  two  speeds  should  be  equal. 

457.  What   should   be   the   form   or   curvature  of   the 
blades,  or  buckets? 

Ans.  They  should  be  of  such  form  as  will  permit  expan- 
sion of  the  steam  with  the  least  amount  of  friction,  or  eddy 
currents. 

458.  How  are  the  stuffing  boxes  of  steam  turbines  usu- 
ally kept  cooled? 

Ans.     By  means  of  water  applied  in  various  ways. 


Questions  and  Answers  131 

459.  How  is  the  speed  of  steam  turbines  usually  regu- 
lated ? 

Ans.     By  simple  throttling. 

460.  What  are  the  ideal  conditions  under  which  a  tur- 
bine should  work? 

Ans.  A  full  initial  pressure,  and  all  cross  sections  of 
steam  passages  to  be  suitable  to  the  power  required. 

461.  Of  what  type  is  the  Westinghousc-Parsons  turbine  ? 
Ans.     It  is  both  an  impulse  and  reaction  turbine. 

462.  How  are  the  clearances  between  the  blades  pre- 
served in  this  turbine? 

Ans.     By  means  of  balancing  pistons  on  the  shaft. 

463.  What  is  the  usual   velocity  of  the  steam   in  the 
Westinghouse-Parsons  turbine  ? 

Ans.     600  ft.  per  second. 

464.  How  does  the  efficiency  of  steam  turbines  compare 
with  that  of  reciprocating  engines? 

Ans.     It  is  generally  higher. 

465.  How  is  the  heat  energy  in  the  steam  imparted  to 
the  wheels  of  the  Curtis  turbine? 

Ans.     Both  by  impulse  and  reaction. 

466.  Describe  the  method  of  admission  in  the  Curtis 
turbine. 

Ans.  The  steam  is  admitted  through  expanding  nozzles 
in  which  nearly  all  of  the  expansive  force  of  the  steam  is 
transformed  into  the  force  of  velocity.  The  steam  is  caused 
to  pass  through  one,  two,  or  more  stages  of  moving  ele- 
ments, each  stage  having  its  own  set  of  expanding  nozzles, 
each  succeeding  set  of  nozzles  being  greater  in  number  and 
of  larger  area  than  the  preceding  set. 

467.  What  is  the  ratio  of  expansion  in  these  nozzles? 


132  Steam  Engineering 

Ans.  The  ratio  of  expansion  within  these  nozzles  de- 
pends upon  the  number  of  stages,  as,  for  instance,  in  a  two- 
stage  machine,  the  steam  enters  the  initial  set  of  nozzles  at 
boiler  pressure,  say  180  Ibs.  It  leaves  these  nozzles  and 
enters  the  first  set  of  moving  blades  at  a  pressure  of  about 
15  Ibs. 

468.  In  a  four-stage  machine,  with  180  Ibs  initial  pres- 
sure, what  would  be  the  pressures  at  the  different  stages? 

Ans.  First  stage,  50  Ibs. ;  second  stage,  5  Ibs. ;  third 
stage,  partial  vacuum,  and  fourth  stage,  condenser  vacuum. 

469.  How  are  the  revolving  parts  of  the  Curtis  turbine 
supported  ? 

Ans.  Upon  a  vertical  shaft,  which  in  turn  is  supported 
by,  and  runs  upon  a  step  bearing  at  the  bottom. 

470.  How  is  this  step  bearing  lubricated? 

Ans.  Oil  is  forced  under  pressure  by  a  steam  or  elec- 
trically driven  pump,  the  oil  passing  up  from  beneath. 

471.  How  is  the  speed  of  the  Curtis  turbine  regulated? 
Ans.     By  varying  the  number  of  nozzles  in  flow. 

472.  How  are  the  clearances   adjusted   in  the   Curtis 
turbine  ? 

Ans.     By  means  of  the  large  step  screw  at  the  bottom. 

473.  How  is  the  shaft  packed  to  prevent  steam  leakage  ? 
Ans.     With  carbon  blocks  made  into  rings  fitting  the 

shaft. 

474.  What  type  of  turbine  is  the  De  Laval  ? 
Ans.  It  is  purely  an  impulse  wheel. 

475.  What  is  the  speed  of  the  wheel  ? 

Ans.     From  10,000  to  30,000  revolutions  per  minute. 

476.  How  is  the  heat  energy  in  the  steam  utilized  in 
the  De  Laval  turbine? 

Ans.     In  the  production  of  velocity. 


Questions  and  Answers  133 

477.  What  is  the  velocity  of  the  steam  as  it  issues  from 
the  expanding  nozzles  and  impinges  against  the  buckets? 

Ans.  About  4,000  ft.  per  second. 

478.  What  is  the  usual  peripheral  speed  of  the  wheel? 
Ans.  1,200  to  1,300  feet  per  second. 

479.  Of  what  type  is  the  Allis-Chalmers  steam  turbine? 
Ans.  It  is  essentially  of  the  Parsons  type. 

480.  How  are  the  clearances  between  the  revolving  and 
stationary  blades  preserved? 

Ans.     By  a  thrust  bearing. 

481.  What  kind   of  bearings  has   the   Allis-Chalmers 
turbine  ? 

Ans.     Self-adjusting  ball  and  socket  bearings. 

482.  What  is  the  first  move  in  preparing  to  start  a 
steam  turbine? 

Ans.  Open  the  throttle  slightly  and  allow  a  small  vol- 
ume of  steam  to  flow  through  in  order  to  warm  the  tur- 
bine. 

483.  What  should  be  done  next? 
Ans.     Start  the  auxiliary  oil  pump. 

484.  What  are  the  principal  precautions  to  be  observed 
when  starting  a  steam  turbine? 

Ans.  To  see  that  the  turbine  is  properly  warmed,  also 
to  be  certain  that  the  oil  is  circulating  freely  through  the 
bearings. 

485.  What  type  of  turbine  is  the  Hamilton-Holzwarth 
steam  turbine? 

Ans.     It  is  an  impulse  turbine. 

488.     Describe  in  brief  its  construction? 

Ans.  There  are  no  balancing  pistons  in  this  machine, 
the  axial  thrust  of  the  shaft  being  taken  up  by  a  thrust 
ball-bearing.  The  interior  of  the  cylinder  is  divided  into 


134  Steam  Engineering 

a  series  of  stages  by  stationary  discs  which  are  set  in 
grooves  in  the  cylinder  and  are  bored  in  the  center  to  allow 
the  shaft,  or  rather  the  hubs  of  the  running  wheels  that  are 
keyed  to  the  shaft,  to  revolve  in  this  bore. 

487.  In  what  respect  does  this  turbine  resemble  a  com- 
pound reciprocating  engine? 

Ans.  The  steam  is  first  admitted  to  the  high  pressure 
casing,  and  from  there  it  passes  into  the  low  pressure  cas- 
ing, which  is  larger  in  diameter. 

488.  Describe  the  action  of  the  steam  upon  the  blades  ? 
Ans.     The  expansion  of  the  steam  takes  place  entirely 

within  the  stationary  blades,  which  also  change  the  direc- 
tion of  its  flow,  distributing  it  to  the  running  vanes. 

489.  What  additional  function  do  the  stationary  vanes 
perform  ? 

Ans.  They  take  the  back  pressure,  thus  acting  as  balanc- 
ing pistons. 

490.  What  type  of  governor  has  this  turbine? 
Ans.     The  spring  and  weight  type. 

491.  How  are  the  bearings  lubricated  ? 

Ans.  The  oil  is  forced  into  the  bearings  under  pressure 
by  an  oil  pump. 

492.  Of  what  type  is  the  Rateau  steam  turbine? 

Ans.  It  is  an  impulse  turbine  having  wheels  of  thin 
plates,  slightly  conical. 

493.  How  is  the  rotor  balanced? 

Ans.  The  same  pressure  exists  on  both  sides  of  each 
rotating  wheel. 

494.  Does  the  steam  act  by  velocity  or  pressure? 
Ans.     By  velocity  in  this  case. 

495.  What  are  the  essential  features  of  the  Eeidler- 
Stumpf  steam  turbine  ? 


Questions  and  Answers  135 

Ans.  The  peculiar  form  of  bucket,  and  the  parallel 
return  of  the  steam. 

496.  What  is  meant  by  parallel  return  of  the  steam? 
Ans.     The   steam   enters   the  buckets   through   nozzles, 

and  is  deflected  through  an  angle  of  180  degrees,  thus  leav- 
ing the  rotating  buckets  in  a  direction  parallel  to  that  of 
its  entrance. 

497.  Describe  the  action  of  the  steam  within  the  Reid- 
ler-Stumpf  turbine. 

Ans.  Instead  of  escaping  after  having  once  passed 
through  the  buckets,  it  is  caught  by  the  guides  or  stationary 
buckets  and  returned  to  the  wheel;  this  process  being  re- 
peated again,  and  again  until  all  of  the  energy  in  the  steam 
has  been  made  to  do  work. 

498.  How  many  types  of  this  turbine  are  there  ? 

Ans.     Two,  viz. :  The  single  flow,  and  the  double  flow. 

499.  How  is  the  highest  efficiency  obtained  in  the  oper- 
ation of  the  steam  turbine  ? 

Ans.  By  allowing  the  exhaust  steam  to  pass  into  a 
condenser. 

500.  Is  it  possible  to  maintain  as  high  vacuum  with 
the  turbine  as  with  a  reciprocating  engine? 

Ans.  Experience  demonstrates  that  a  higher  vacuum 
may  be  maintained  in  the  condenser  of  a  turbine  than  is 
possible  with  reciprocating  engines. 

501.  What  kind  of  condensing  apparatus  may  be  used 
with  steam  turbines? 

Ans.     Any  one  of  the  modern  improved  types. 

502.  What   is  required  in  order  to  maintain   a  high 
vacuum  in  any  type  of  condenser? 

Ans.     That  all  entrained  air  be  excluded. 

503.  How  may  this  be  accomplished? 


136  Steam  Engineering 

Ans.     By  means  of  a  dry  air  pump. 

504.  In  what  manner  does  the  dry  air  pump  differ  from 
an  ordinary  air  pump? 

Ans.     The  dry  air  pump  handles  no  water,  and  the  clear- 
ances are  made  as  small  as  possible. 

505.  To  what  extent  does  the  steam  turbine  expand  its 
working  steam? 

Ans.     To  within  one  inch  of  the  vacuum  existing  within 
the  condenser. 

506.  Is  the  steam  turbine  adapted  to  the  use  of  super- 
heated steam? 

Ans.     It  is.    Highly  superheated  steam  may  be  used,  and 
a  high  vacuum  maintained. 

507.  Is  the  water  of  condensation  from  turbines  desir- 
able for  boiler  feed  ? 

Ans.     It  is,  for  the  reason  that  it  contains  no  lubricating 
oil,  and  is  a  comparatively  pure  water. 


INDEX 


A 

Allis-Chalmers  Steam  Turbine 75-88 

Action  of  steam  in 78 

Balance  pistons 79 

Bearings    81-82 

Blades 78-81 

Description  of    75-77 

General  view  of 76 

Governor 81 

Starting  and  operating   84-88 

Thrust  bearing  79 

B 

Blade — Form  of 12-13 

Branca's   Turbine 10 

C 

Catechism    129-136 

Condensers 123 

Curtis  Steam  Turbine   37-58 

Action  of  steam  in  34-44 

Admission  valves   43 

Baffler    58 

Clearance 55-56 

Governor    48-52 

Initial  nozzles  and  buckets 36-40 

Shaft    37 

Speed  regulation    44-48 

Step  bearing    55 

Wheels  and  stages   38-41 

D 

De  Laval  Steam  Turbine   59-60 

Action  of  steam  in   66-68 

Description  of  parts    62-68 

i 


ii  Index 

Efficiency  tests  of  72-73 

Gear — Flexible  shaft    66-67 

Governor    , 68-69 

High  speed  of   59-62 

Nozzles    60 

Wheel    73 

E 
Efficiency  of  Steam  Turbines  29-30 

F 
Form  of  turbine  blade 12-13 

G 

General    suggestions    88 

Governor    27,  48,  68 

H 

Hamilton-Holzwarth  Steam  Turbine 89-105 

Action  of  steam  in 83-84 

Catechism  on 133-135 

Clearance  of  blades   92-94 

Comparison  with  other  types  91-92 

Construction  of  blades    94-95 

Governor — Regulation    85-87 

Running   wheels 95-9!) 

Stationary  discs S4-N5 

Stuffing  box 103-105 

I 

Initial  Nozzles  and  Buckets 36-40 

Invention  of  the  steam  turbine   7,  20 

L 
Labyrinth  Stuffing  Box  13-14 

O 
Operation   of    Steam    Turbines 17,48,88 


Index  iii 

P 

Piping    51 

Precautions 50 

R. 

Rateau  Steam  Turbine 107-117 

Action  of  steam  in 108-110 

Principles  of  108 

Regenerator  for  low  pressures 110-116 

Regulation  of  Steam  Turbines  17 

S 

Steam  Turbine  7-12 

Allis-Chalmers  75-88 

Curtis  37-58 

De  Laval  59-60 

Hamilton-Holzwarth  89-105 

Rateau  107-117 

Reidler-Stumpf 119-122 

Starting — Rules  for  84 

Stopping — Rules  for  87-88 

Stuffing  Boxes 13-17 

Allis-Chalrners  82 

Curtis  58 

De  Laval  68 

Hamilton-Holzwarth  103-105 

Rateau  15-16 

W 

Westinghouse- Parsons  Steam  Turbine 19-36 

Admission    nozzles 33-37 

Balancing    pistons 24-25 

Blade  material  29-30 

Capacity    of 19 

Catechism   on 131-132 

Direction  of  steam  through 24 

Double   flow   type 30-36 

Efficiency    of 29 

( Jovernor    27-28 


Practical     Mechanical     Drawing 
and  Machine  Design  Self-Taught 

By  CHARLES  WESTINGHOUSE 
Over    200    Illustrations    and    160    Pages.     Price,  $2  00 


A  COMPLETE  SELF- INSTRUCTOR  FOR  HOME 
STUDY  on  Drafting  tools  —  Geometrical  defini- 
tion of  plane  figures — Properties  of  the  circle — Poly- 
gons—  Geometrical  definitions  of  solids  —  Geometrical 
drawing — Geometrical  problems — Mensuration  of  plane 
surfaces — Mensuration  of  volume  and  surface  of  solids 
— The  development  of  curves — The  development  of  sur- 
faces— The  intersection  of  surfaces — Machine  drawing 
— Technical  definitions — Material  used  in  machine  con- 
struction— Shafting — Machine  design — Transmission  of 
motion  by  belts — Horsepower  transmitted  by  ropes — 
Horsepower  of  gears — Transmission  of  motion  by  gears 
— Diametral  pitch  system  of  gears — Worm  gearing — 
:  Steam  boilers — Steam  engines — Tables. 

Frederick  J.  Drake   &   Co.,  Publishers 

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ELEMENTARY  ELECTRICITY 

UP   TO    DATE 

By  SIDNEY  AYLMER-SMALL,  M.  A.  I.  E.  E. 


THIS  book  opens  up  the  way  for 
anyone  who  desires  an  accurate 
and  complete  knowledge  of  elec- 
tricity as  a  useful  agent,  in  the  hands 
of  man,  for  the  transmission  of  me- 
chanical energy,  and  the  creation  of 
light. 

In  addition  to  opening  up  the  way 
as  referred  to  above,  the  book  also 
serves  as  a  guide  and  instructor  to  the 
seeker  after  knowledge  along  these 
lines. 

Beginning  in  the  form  of  a  simple 
catechism  on  the  primary  aspects  of 
the  subject  it  conducts  the  student  by 
easy  stages  through  the  various  as- 
pects of  static  electricity,  the  different 
types  of  apparatus  for  producing  it, 
all  of  which  are  plainly  described  and 

illustrated  and  their  action  made  plain  and  easy  of  comprehension. 
Quite  a  large  space  is  devoted  to  this  important  topic,  although  no 
more  than  is  actually  necessary,  as  the  subj  ects  of  condensers  and  simple 
electrical  machines  are  also  thoroughly  handled,  and  the  principles 
governing  their  action  clearly  explained  and  illustrated.  The  subject  of 
atmospheric  electricity  is  next  dealt  with,  and  lightning  arresters  treated 
upon,  especially  in  their  relation  to  electric  power  stations,  sub-stations 
and  line  wires.  The  wonderful  and  mysterious  subject  of  magnetism 
is  next  treated  upon  at  length  and  clearly  explained— the  explanations 
being  accompanied  by  illustrations. 

Primary  batteries  of  all  types,  storage  batteries  and  the  effects  of  elec- 
trolysis each  and  all  receive  a  large  share  of  attention.  Electric  circuits 
and  the  laws  governing  the  flow  of  current,  including  Ohm's  law,  are  all 
clearly  explained.  The  student  has  now  arrived  at  the  point  where 
electrical  work,  power  and  efficiency  is  the  topic,  and  where  the  genera- 
tion and  transmission  of  electrical  currents  of  high  potential  and  large 
volume  are  explained. 

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Practical  Armature 
and  Magnet  Winding 

By  HENRY  C.  HORSTMANN  and  VICTOR  H.  TOUSLEY 


my  PRACTICAL  <u% 


WHILE  the  subject  of  armature  wind- 
ing has,  in  the  past,  been  more  or 
less  completely  covered,  most  of 
these  works  have  been  either  too  technical 
in  their  composition  or  have  required  a 
fair  degree  of  knowledge  of  the  subject 
before  they  could  be  clearly  understood. 
There  has  been  a  need  of  a  book  cover- 
ing this  matter  which,  while  giving  all  that 
is  necessary  for  an  intelligent  under- 
standing, would,  at  the  same  time,  present 
the  matter  in  such  a  simple  form  that  it 
could  be  readily  grasped  by  those  who 
had  not  had  the  benefit  of  a  previous 
education  along  this  line. 

This  book  treats  in  a  practical  and  con- 
cise manner  this  very  important  subject. 

All  practical  armature  windings  are  fully  explained  with  special  atten- 
tion paid  to  details.  All  questions  which  are  apt  to  arise  in  the  minds 
of  the  students  have  been  completely  answered. 

Numerous  illustrations  have  been  supplied,  and  these,  taken  in  con- 
junction with  the  text,  afford  a  ready  means  for  either  the  study  of  the 
armature  or  for  a  book  of  reference. 

It  has  been  the  aim  of  the  authors  to  supply  all  the  necessary  informa- 
tion required  by  the  subject  and,  at  the  same  time,  to  give  this  informa- 
tion in  as  condensed  and  brief  a  form  as  is  consistent  with  a  clear 
understanding. 

Various  useful  tables  have  been  especially  prepared  for  this  work  and 
these  will  not  only  reduce  to  a  minimum  the  number  of  calculations  re- 
quired, but  lessen  the  possibility  of  errors. 

A  chapter  on  the  calculation  of  armatures  gives  complete  information 
in  detail  for  thp  design  of  an  armature. 

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Corners,  Red  Edges $1.50 

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OPERATORS'  WIRELESS  TELEGRAPH 
AND  TELEPHONE  HAND-BOOK 


By  VICTOR  H.  LAUGHTER 


UP-TO-DATE  and  most  com- 
plete treatise  on  the  subject 
yet  published.  Gives  the 
historical  work  of  early  investi- 
gators on  up  to  the  present  day. 
Describes  in  detail  the  construc- 
tion of  an  experimental  wireless 
set.  How  to  wind  spark  coil  and 
dimensions  of  all  size  coils.  The 
tuning  of  a  wireless  station  is 
fully  explained  with  points  on 
the  construction  of  the  various 
instruments. 

A  special  chapter  on  the  study 
of  wireless  telegraphy  is  given 
and  the  rules  of  the  Naval  sta- 
tions with  all  codes,  abbrevia- 
tions, etc. ,  and  other  matter  in- 
teresting to  one  who  takes  up  this  study. 

The  most  difficult  points  have  been  explained  in  non- 
technical language  and  can  be  understood  by  the  layman. 
Wireless  telephony  is  given  several  chapters  and  all  the 
systems  in  use  are  shown  with  photographs  and  drawings. 
By  some  practical  work  and  a  close  study  of  this  treatise 
one  can  soon  master  all  the  details  of  wireless  telegraphy. 


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12mo.,  Cloth,  210  Pages,  Fully  Illustrated,  and  with  Six 
additional  Full-Page  Halftone  Illustrations  Showing  the  In- 
stallation of  "Wireless"  on  the  U.  S.  War  Ships  and  Ocean 
Liners $1.00 


FREDERICK  J.  DRAKE  &  CO. 


PUBLISHERS 


CHICAGO,  ILLINOIS 


STEAM  BOILERS,  THEIR 
CONSTRUCTION,  CARE 
AND  OPERATION, 


with  questions 
and    answers. 


BY  C.  F.  SWINGLE,  M.  E. 


A  complete  modern  treatise  fully  describing,  with  illus- 
trations, the  steam  boiler  of  various  types.    Construction 

and  rules  for  ascertaining 
the  strength  for  finding 
safe  working  pressure. 
Boiler  settings  and  ap- 
purtenances, grate  sur- 
face insulation,  cleaning 
tubes,  safety  valve  cal- 
culations, feed  pumps, 
combustion,  evaporation 
tests  with  rules,  strength 
of  boilers,  and  mechani- 
cal stokers.  200  pages, 
fully  illustrated. 

The  latest  and  most 
complete  treatise  on  boil- 
ers    published.       16mo. 
Full  leather  limp  binding. 
PRICE   NET 


$1.50 


Sent  Postpaid  to  any  Address  in  the  World  upon  Receipt  of  Price 

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DYNAMO  TENDING 

for 

ENGINEERS 

Or,  ELECTRICITY 
FOR  STEAM  ENGINEERS 

By  HENRY  C.  KORSTMANN  and 

VICTOR  H.  TOUSLEY, 
Authors  of  "Modern  Wiring  Diagrams  and 
Descriptions  for  Electrical  Workers." 

This  excellent  treatise  is  written  by 
engineers  for  engineers,  and  is  a  clear 
and  comprehensive  treatise  on  the  prin- 
ciples, construction  and  operation  of 
Dynamos,  Motors,  Lamps,  Storage  Bat- 
teries, Indicators  and  Measuring  Instru- 
ments, as  well  as  full  explanations  of  the 
principles  governing  the  generation 
of  alternating  currents  and  a  descrip- 
tion of  alternating  current  instruments  and  machinery.  There  are 
perhaps  but  few  engineers  who  have  not  in  the  course  of  their  labors 
come  in  contact  with  the  electrical  apparatus  sucL  as  pertains  to  light 
and  power  distribution  and  generation.  \t  the  present  rate  of  increase 
In  the  use  of  Electricity  it  is  but  a  question  of  time  when  every  steam 
installation  will  have  in  connecton  with  it  an  electrical  generator,  even 
in  such  buildings  where  light  and  power  are  supplied  by  some  central 
station.  It  is  essential  that  the  man  in  charge  of  Engines,  Boilers, 
Elevators,  etc.,  be  familiar  with  electrical  matters,  and  ft  cannot  well 
i)e  other  than  an  advantage  to  him  and  his  employers.  It  is  with  a  view 
to  assisting  engineers  and  others  to  obtain  such  knowledge  as  will  enable 
them  to  intelligently  manage  such  electrical  apparatus  as  will  ordinarily 
come  under  their  control  that  this  book  has  been  written.  The  authors 
have  had  the  co-operation  of  the  best  authorities,  each  in  his  chosen  field, 
and  the  information  given  is  just  such  as  a  steam  engineer  should  know. 
To  further  this  information,  and  to  more  carefully  explain  the  text, 
nearly  100  illustrations  are  used,  which,  with  perhaps  a  very  few  excep- 
tions, have  been  especially  made  for  this  book.  There  are  many  tables 
covering  all  sorts  of  electrical  matters,  so  that  immediate  reference  can 
be  made  without  resorting  to  figuring.  It  covers  the  subject  thoroughly, 
but  so  simply  that  any  one  can  understand  it  fully.  Any  one  making  a 
pretense  to  electrical  engineering  needs  this  book.  Nothing  keeps  a  man 
down  like  the  lack  of  training;  nothing  lifts  him  up  as  quickly  or  as 
surely  as  a  thorough,  practical  knowledge  of  the  work  he  has  to  do.  This 
book  was  written  for  the  man  without  an  opportunity.  No  matter  what 
he  is,  or  what  work  he  has  to  do,  it  gives  him  just  such  information 
and  training  as  are  required  to  attain  success.  It  teaches  just  what 
the  steam  engineer  should  know  in  his  engine  room  about  electricity.  ., 
12mo,  Cloth,  10O  Illustrations.  Size5%x7%.  PRICE  NET  £l  PA 
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receipt  of  price  _• 

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CHICAGO,  ILL. 


The  Calculation  of  Horse 
Power  Made  Easy   :   :   : 

By   L.   ELLIOTT   BROOKES 

Author    of    "Gas    and    Oil    Engine    Hand-Book," 
"The  Automobile  Hand-Book,"  Etc. 

Size,  5x7%.     80  Pages,  Illustrated.     Cloth,  75  Cents 


THIS  work  deals  in  a  practical  and  non- 
technical manner  with  the  calculation 
of  the  power  of  Steam  Engines,  *Explo- 
sive  and  Electric  Motors. 

Particular  attention  has  been  given  to  the 
full  explanation  of  the  elementary  principles 
upon  which  the  calculations  are  based. 

It  has  been  the  endeavor  to  present  in  as 
simple  a  manner  as  is  possible,  a  number  of 
useful  rules  and  formulas  that  may  be  of 
great  va,lue  to  ENGINEERS,  MACHINISTS  and 
DESIGNERS  in  calculating  horse  power. 

Rules  for  plotting  steam  engine  diagrams 
by  arithmetical,  geometrical  and  graphical 
methods  are  given  and  fully  explained,  also 
the  method  used  in  plotting  the  diagram  of 
an  explosive  motor. 

This  work  covers  many  points  regarding 
the  calculation  of  horse  power  and  useful 
information  not  hitherto  published  in  a  single 

volume,  and  includes  Calculated,  Brake  and  Indicated  horse  power,  Point  of 
cut-off  and  average  steain  pressure,  Horse  Power  of  Explosive  Motors,  Degree 
of  Compression  and  Combustion  Chamber  Dimensions,  Indicator  Diagrams  of 
Steam  Engines  and  Explosive  Motors,  also  tables  of  Average  Steam  Pressure, 
Areas  of  Circles,  Squares  of  Diameters  of  Circles,  Natural  Logarithms  of  Num- 
bers, Thermo-dynamic  Properties  of  Gasoline  and  Air,  Common  Logarithms 
of  Numbers,  and  Mensuration  of  Surface  and  Volume. 

The  term  "  Explosive  Motor  "  includes  Gas,  Gasoline  and  Oil  Engines. 


SENT    POSTPAID    TO    ANY    ADDRESS    IN 
THE    WORLD    UPON    RECEIPT   OF    PRICE 

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PUBLISHERS.  CHICAGO,  ILL. 


MODERN  ELECTRICAL 
CONSTRUCTION 

By  HORSTMANN  and  TOUSLEY  - 

77THIS   book  treats  almost  entirely    of    practical    electrical 
^^    work.     It  uses  the  '  'Rules  and  Requirements  of  the  Na- 
tional Board  of  Fire  Underwriters"  as  a  text,  and  ex- 
plains by  numerous  cuts  and  detailed  explanations  just  how 

the  best  class  of  electrical 
work  is  installed. 

It  is  a  perfect  guide  for 
the  beginning  electrician 
and  gives  him  all  the 
theory  needed  in  practical 
work  in  addition  to  full 
practical  instructions.  For 
the  journeyman  electrician 
it  is  no  less  valuable,  be- 
cause it  elaborates  and 
explains  safety  rules  in 
vogue  throughout  the 
United  States.  It  is  also 
of  especial  value  to  elec- 
trical inspectors,  as  it 
points  out  many  of  the 
tricks  practiced  by  un- 
scrupulous persons  in  the 
trade. 

The  book  also  contains  a 
number  of  tables  giving  di- 
mensions and  trade  num- 
bers of  screws,  nails,  in- 
sulators and  other  material 
in  general  use,  which  will  be  found  of  great  value  in  practice. 
There  is  also  given  a  method  by  which  the  diameter  of  con- 
duit necessary  for  any  number  of  wires  of  any  size  can  be  at 
once  determined.  The  motto  of  the  authors,  "To  omit  noth- 
ing that  is  needed  and  include  nothing  that  is  not  needed, " 
that  has  made  "Wiring  diagrams  and  Descriptions"  so  suc- 
cessful, has  been  followed  in  this  work.  No  book  of  greater 
value  to  the  man  who  does  the  work  has  ever  been  published. 
16mo,  250  pages,  100  diagrams.  Full  leather,  limp. 
"  =  Price,  nett  $/,5O  '  •  aaai 

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FREDERICK  J.  DRAKE  &  CO. 


PUBLISHERS 


CHICAGO, 


ILLINOIS. 


COMPLETE  EXAMINATION 
QUESTIONS  AND  ANSWERS 

FOR  MARINE  AND 
STATIONARY  ENGINEERS 


By  Calvin  F.  Swingle,  M.  E.  Author  of  Swingle's  Twentieth 
Century  Hand  Book  for  Steam  Engineers  and  Electricians. 
Modern  Locomotive  Engineering  Handy  Book,  and 
Steam  Boilers — Their  construction,  care  and  management 

/TfHIS  book  is  a  compendium  of 
^  useful  knowledge,  and  prac- 
tical pointers,  for  all  engineers, 
whether  in  the  marine,  or  station- 
ary service.  For  busy  men  and  for 
those  who  are  not  inclined  to  snend 
any  more  time  at  study  than  is  ab- 
solutely necessary,  the  book  wiL 
prove  a  rich  mine  from  which  they 
may  draw  nuggets  of  just  the  kind 
of  information  that  they  are  look- 
ing for. 

The  method  pursued  by  the  au- 
thor in  the  compilation  of  the  work 
and  in  the  arrangement  of  the  sub- 
ject matter,  is  such  that  a  man  in 
search  of  any  particular  item  of  in- 
formation relative  to  the  operation 
of  his  steam  or  electric  plant,  will 
experience  no  trouble  in  rinding 
that  particular  item,  and  he  will  not 
be  under  the  necessity  of  going 
over  a  couple  of  hundred  pages, 
either,  before  he  finds  it  because 
the  matter  is  systematically  ar- 
ranged and  classified. 
The  book  will  be  a  valuable  addition  to  any  engineer's  library,  nor 
alone  as  a  convenient  reference  book,  but  also  as  a  book  for  study.  It 
also  contains  a  complete  chapter  on  refrigeration  for  engineers.  300 
pages  fully  illustrated,  durably  bound  in  full  Persian  Morocco  limp, 
round  corners,  red  edges. 

PRICE $1.50 

N.  B.— This  is  the  very  latest  and  best  book  on  the  subject  in  print. 

Sold  by  Booksellers  generally  or  sent  postpaid  to 
any  address  upon  receipt  of  price  by  the  Publishers 

FREDERICK  J.  DRAKE  &  CO. 

CHICAGO,  U.S.A. 


Twentieth  Century 
Machine  Shop  Practice 

By  L.  ELLIOTT   BROOKES 

The  best  and  latest  and  most 
practical  work  published  on  mod- 
ern machine  shop  practice.  This 
book  is  intended  for  the  practical 
instruction  of  Machinists,  Engin- 
eers and  others  who  are  interested 
in  the  use  and  operation  of  the 
machinery  and  machine  tools  in  a 
modern  machine  shop.  The  first 
portion  of  the  book  is  devoted  to 
practical  examples  in  Arithmetic, 
Decimal  Fractions,  Roots  of  Num- 
bers, Algebraic  Signs  and  Symbols, 
Reciprocals  and  Logarithms  of 
Numbers,  Practical  Geometry  and 
and  Mensuration.  Also  Applied 
Mechanics — which  includes :  The 
lever,  The  wheel  and  pinion,  The 
pulley,  The  inclined  planes,  The 
wedge  The,  screw  and  safety  valve 
—Specific  gravity  and  the  velocity 
of  falling  bodies — Friction,  Belt 
Pulleys  and  Gear  wheels. 

Properties  of  steam.  The  Indi- 
cator, Horsepower  and  Electricity. 

Tb-.  latter  part  of  the  book  gives  full  and  complete  information 
upon  the  following  subjects:  Measuring  devices,  Machinists'  tools, 
Shop  tools,  Machine  tools,  Boring  machines,  Boring  mills.  Drill 
presses,  Gear  Cutting  machines,  Grinding  Machines,  Lathes  and  Mill- 
ing machines.  Also  auxiliary  machine  tools.  Portable  tools,  Miscella- 
neous tools,  Plain  and  Spiral  Indexing  machines,  Notes  on  Steel.  Gas 
furnaces,  Shop  talks,  Shop  kinks,  Medical  Aid  and  over  Fifty  tables. 

The  book  is  profusely  illustrated  and  shows  views  of  the  latest 
machinery  and  the  most  up-to-date  and  improved  belt  and  motor- 
driven  machine  tools,  with  full  information  as  to  their  use  and  opera- 
tion. It  has  been  the  object  of  the  author  to  present  the  subject 
matter  in  this  work  in  as  simple  and  not  technical  manner  as  is 
possible. 

12mo,  cloth,  636  pages,  456  fine  illustration?,  price,  $2.00 

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any  address  upon  receipt  of  Price  by  the  Publishers 

FREDERICK  J.  DRAKE  &  CO. 

PUBLISHERS  CHICAGO,  U.  S.  A. 


THE  KING  OF  ALL—  The  Companion  Volume  to  Modern 
Wiring  Diagrams — Just  from  the  Press 

Electrical  Wiring  *»<r 
Construction  Tables 

By  Henry  C.  Horstmann  and  Victor  H.  Tousley 

Contains  hundreds  of  easy  up-to-date  tables  covering  everything  on 

Electric  Wiring.     Bound  in  full  Persian  Morocco. 

Pocket  size.     Round  corners,  red  edges. 

PRICE,  NET,  $1.50 

Partial  Table  of  Contents 

This  Book  contains 

among  others: 

Tables  for  direct  current 
calculations. 

Tables  for  alternating  cur- 
icnt  calculations. 
These  tables  show  at  a 
glance  the  currents  re- 
quired with  any  of  the 
systems  in  general  use, 
fcr  any  voltage,  effici- 
ency, or  power-factor, 
and  by  a  very  simple 
calculation  (which  can 
be  mentally  made),  also 
the  proper  wire  for  any 
less. 

Tables  showing  the  small- 
est wire  permissable 
with  any  system  or  num- 
ber of  H.  P.  or  lights 
under  "National  Electri- 
cal Code"  or  Chicago 
rules.  Very  convenient 
for  contractors. 

Tables  for  calculating  the 
most  economical  loss. 

Tables    and    diagrams 
showing   proper   size   of 
conduits    to    accommo- 
date   all    necessary  combinations    or 
number  of   wires. 

Tables  and  data  for  estimating  at  a 
glance  the  quantity  of  material  re- 
quired in  different  lines  of  work. 

A3  this  is  intended  for  a  pocket-hand-book  everything  that  would 
•**•  makes  it  unnecessarily  cumbersome  is  omitted.  There  is  no 
padding.  Every  page  is  valuable  and  a  time  saver.  This  book  will 
be  used  every  day  be  the  wireman,  the  contractor,  engineer  and 
architect.  All  parts  are  so  simple  thai  verv  ''ttle  electrical  knowl- 
edge is  required  to  understand  them. 

tpon  receipt  of  price. 


8 int.  all  chrages  paid  to  any  address, 

FREDERICK  J.  DRAKE  &  CO.,  Publishers, 


Chicago 


The  Practical  Gas  & 

Oil  Engine   HAND-BOOK 


II 


••••.•.••'S;:-'-P;V.v"-:.v.';:  •.-."•  .'•.*."  •"'•'."  ••"•'• 


A  MANUAL  of  useful  in- 
•**•  formation  on  the  care, 
maintenance  and  repair  of  Oas 
and  Oil  Engines. 

This  work  gives  full  and 
clear  instructions  on  all  points 
relating  to  the  care,  mainte- 
nance and  repair  of  Stationary, 
Portable  and  Marine,  Gas  and 
Oil  Engines,  including  How  to 
Start,  How  to  Stop,  How  to  Ad- 
just, How  to  Repair,  How  to 
Test.  , 

Pocket  size,  4x6H.  Over 
200  pages.  With  numerous 
rules  and  formulas  and  dia- 
grams, and  over  50  illustrations 
by  L.  ELLIOTT  BROOKES,  au- 
thor of  the  "Construction  of  a 
Gasoline  Motor,"  and  the  "Au- 
tomobile Hand-Book." 

This  book  has  been  written 
with  the  intention  of  furnishing 
practical  information  regarding 
gas,  gasoline  and  kerosene  engines,  for  the  use  of  owners,  operators  and 
others  who  may  be  interested  in  their  construction,  operation  and  man- 
agement. 

In  treating  the  various  subjects  it  has  been  the  endeavor  to  avoid  all 
technical  matter  as  far  as  possible,  and  to  present  the  information  given 
in  a  clear  and  practical  manner. 

1 6mo.    Popular  Edition— Cloth.     Price $1.00 

Edition  de  Luxe    Full  LesxtHer  Limp.     Price 1.50 

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Easy  Electrical  Experiment* 
and  How  to  Make  Them 

By  L.  P.  DICKINSON 

This  is  the  very  latest  and  mosi 
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and  Practical  Telephones,  Telegraph 
Instruments,  Rheostat,  Condensers,  Electrophorous, 
Resistance,  Electro  Plating,  Electric  Toy  Making,  etc. 
The  book  is  an  elementary  hand  book  of  lessons, 
experiments  and  inventions.  It  is  a  hand  book  for 
beginners,  though  it  includes,  as  well,  examples  for 
the  advanced  students.  The  author  stands  second  to 
none  in  the  scientific  world,  and  this  exhaustive  work 
will  be  found  an  invaluable  assistant  to  either  the 
Student  or  mechanic. 

Illustrated  with  hundreds  of  fine  drawings;  printed! 
on  a  superior  quality  of  paper. 

J2mo  Cloth.       Price,  $1.25, 

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66*5*- 


YB   1076 


